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000
FXUS63 KUNR 180416
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1016 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1011 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. ACROSS WRN SD...MVFR
CIGS/VSBYS ARE EXPECTED ACROSS ALL BUT FAR NWRN SD. PARTS OF NERN
WY WILL ALSO REMAIN VFR. SOME LIFR CIGS/VSBYS EXPECTED OVER THE
HIGHER TERRAIN OF THE BLACK HILLS. CONDITIONS WILL IMPROVE FROM
NORTHWEST TO SOUTHEAST BEGINNING LATE SATURDAY AFTN BEHIND A
CDFNT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS63 KUNR 180416
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1016 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1011 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. ACROSS WRN SD...MVFR
CIGS/VSBYS ARE EXPECTED ACROSS ALL BUT FAR NWRN SD. PARTS OF NERN
WY WILL ALSO REMAIN VFR. SOME LIFR CIGS/VSBYS EXPECTED OVER THE
HIGHER TERRAIN OF THE BLACK HILLS. CONDITIONS WILL IMPROVE FROM
NORTHWEST TO SOUTHEAST BEGINNING LATE SATURDAY AFTN BEHIND A
CDFNT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON



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000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML



000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML



000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML



000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML



000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML




000
FXUS65 KCYS 180006
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
606 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM MDT FRI APR 17 2015

A LITTLE REPREIVE IN THE WEATHER EARLY THIS EVENING BEFORE
CONVECTION WANES AND STRATUS BEGINS TO SETTLE INTO THE AREA.
LOOKING AT FAIRLY WIDESPREAD IFR/LIFR LATER THIS EVENING FOR MOST
AIRPORTS ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. SHOULD
CONTINUE INTO SATURDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...GCC
FIRE WEATHER...SML



000
FXUS63 KUNR 172229
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
429 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 427 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP ACROSS MUCH OF
THE AREA...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 172229
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
429 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 427 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP ACROSS MUCH OF
THE AREA...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS63 KUNR 172229
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
429 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 427 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP ACROSS MUCH OF
THE AREA...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS63 KUNR 172229
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
429 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 427 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP ACROSS MUCH OF
THE AREA...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS65 KCYS 172204
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
404 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.

&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...SML



000
FXUS65 KCYS 172204
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
404 PM MDT FRI APR 17 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM MDT FRI APR 17 2015

A WILD AND CRAZY WEATHER DAY CONTINUES ACROSS MUCH OF SOUTHEAST WY
AND THE WESTERN NE PANHANDLE. PTYPE HAS BEEN AND CONTINUES TO BE A
HUGE CHALLENGE WITH RAIN...SNOW...HAIL AND THUNDER ALL OBSERVED AT
KCYS OVER THE LAST COUPLE OF HOURS. FARTHER WEST...SNOW IS DOMINANT
AS THERMAL PROFILES ARE MORE THAN COLD ENOUGH WITH VDW SITTING AT 28
DEGREES AT 21Z. HIGH-IMPACT WINTER WEATHER CONDITIONS CONTINUE FOR
THE INTERSTATE 80 CORRIDOR BETWEEN RWL AND CYS. ONGOING WINTER STORM
WARNINGS AND ADVISORIES REMAIN IN EFFECT. DOWNGRADED CHEYENNE TO AN
ADVISORY AS SNOW LEVELS HAVE CLIMBED TO AROUND 6250 FEET...
RESULTING IN RAIN CUTTING BACK ON ADDITIONAL SNOW ACCUMULATIONS.
LATEST WATER VAPOR SATELLITE LOOP SHOWS A VIGOROUS UPPER LOW
SPINNING OVER THE 4 CORNERS REGION. A MID LEVEL DRY SLOT CONTINUES
TO PUSH NORTH ACROSS EASTERN CO INTO THE SOUTHERN PANHANDLE. THIS
IS HELPING TURN THINGS MORE SHOWERY BUT IS ALSO CONTRIBUTING TO
MODERATE INSTABILITY WITH SEVERAL HUNDRED J/KG SBCAPES PER SPC
MESOANALYSIS. COULD SEE A FEW STRONG STORMS ALONG THE I80 CORRIDOR
EAST OF CHEYENNE IN THE LATE AFTN AND EARLY EVE...SO WILL KEEP
MENTION OF SMALL HAIL/GUSTY WINDS GOING. A LITTLE CONCERNED ABOUT
THIS WARM FRONTAL SETUP WITH REALLY GOOD LLVL CONVERGENCE OVER OUR
SOUTHEAST. EAST-TO-NORTHEAST FLOW AT THE SFC IS CONTRIBUTING TO
AROUND 15 KTS OF 0-1 KM SHEAR...SO WOULD NOT BE SURPRISED TO SEE
AN ISOLATED WEAK TORNADO NEAR BOUNDARIES OR CELL MERGERS.

ON THE WINTER SIDE...EXPECT MOST OF THE SNOW IN THE NEAR TERM TO BE
ALONG AND WEST OF THE LARAMIE RANGE. IT IS IN THAT LOCATION THAT THE
BEST H7-H3 MOISTURE AND DYNAMIC FORCING COINCIDE. DO NOT EXPECT MUCH
ADDITIONAL ACCUMULATION WITH DRIER AIR MOVING IN...BUT ROAD SURFACES
ARE LIKELY TO REMAIN TREACHEROUS ESPECIALLY OVER THE I80 SUMMIT. THE
MODELS BRING THE MAIN VORT LOBE NORTHWARD AFTER 00Z. GFS/NAM/ECM ALL
SHOW LLVL WINDS TURNING EASTERLY/UPSLOPE BY 06Z...SO WOULD EXPECT AN
UPTICK IN PCPN ALONG/EAST OF THE LARAMIE RANGE OVERNIGHT. BEST GUESS
IS WE WILL NOT SEE A LOT OF ADDITIONAL ACCUMULATION...BUT WITH A LOT
OF RAIN/SLUSH AND POTENTIAL FOR SUB FREEZING TEMPS / ESPECIALLY WITH
A PRONOUNCED DRY SLOT AND SOME CLEARING / ROADS COULD BE QUITE NASTY
FOR THE MORNING COMMUTE. THAT WAS OUR REASONING FOR KEEPING A WINTER
WEATHER ADVISORY GOING FOR THE CITY OF CHEYENNE. EXTENDED ALL OTHER
WARNINGS THROUGH 12Z SAT AS ACCUMULATING SNOW WILL CONTINUE THROUGH
AT LEAST THAT TIME. THE LAST FEW RUNS OF THE NAM HAVE BEEN MORE THAN
A LITTLE BULLISH WITH DEFORMATION BANDING ON THE BACK SIDE OF THIS
SYSTEM ON SAT AFTN/EVE. PRECIP SHOULD BE ALL SNOW AS A KICKER SYSTEM
DIVES ACROSS EASTERN MT AND FORCES H7 TEMPS BELOW -3 C WITH A COLD
FROPA. WILL LET LATER SHIFTS EVALUATE HOW SIGNIFICANT THIS PCPN WILL
BE AND IF WINTER HEADLINES NEED TO BE EXTENDED FURTHER. ALL MODELS
DO PAINT AT LEAST 0.5 TO 1.0 INCHES OF QPF BETWEEN 12Z SAT AND 12Z
SUN THOUGH...SO THIS WILL DEFINITELY BE INTERESTING TO WATCH.

THUNDERSTORMS COULD BE AN ISSUE TOMORROW AS WELL. THE NAM SHOWS CAPE
VALUES OVER 500 J/KG OVER THE PLAINS FOR MUCH OF THE DAY. H7-H3 HPA
RH PROGS SHOW CONSIDERABLE DRYING WHICH WOULD IMPLY POTENTIAL FOR
BETTER SURFACE HEATING THAN TODAY. THINK A FEW STRONG STORMS ARE A
POSSIBILITY WITH 0-6 KM SHEAR AROUND 50 KTS. OVERALL CONVECTIVE PTNL
WILL DEPEND ON THE TIMING OF THE MID LEVEL ENERGY FROM CO AND THE
EVOLUTION OF THETA-E RIDGING OVER THE WESTERN PANHANDLE. MODELS ARE
ADVERTISING THE STABLE AIR MOVING RIGHT OVER OUR EASTERN ZONES...SO
THIS COULD BE A LIMITING FACTOR FOR TSTMS. A NARROW RIBBON OF WARM
AND MOIST AIR ALOFT WILL BE PRESENT OVER WESTERN AREAS...ENHANCING
PCPN RATES IN THE DEFORMATION AXIS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 PM MDT FRI APR 17 2015

SKIES WILL BEGIN TO CLEAR OUT SUNDAY AS THE UPPER LOW IS KICKED
INTO THE PLAINS BY THE NEXT NORTHWEST FLOW DISTURBANCE. SOME
LINGERING SHOWERS ARE A POSSIBILITY SUNDAY BUT OVERALL IT WILL BE
MUCH DRIER. THE KICKER DISTURBANCE WILL MOVE ACROSS SOUTHEAST
WYOMING SUNDAY NIGHT. THIS DISTURBANCE COULD PRODUCE ANOTHER SHOT
OF SNOW...MAINLY ALONG AND WEST OF THE LARAMIE RANGE. COULD SEE
SEVERAL INCHES OF SNOW INTO THE SNOWY AND SIERRA MADRE RANGES BUT
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION OUTSIDE OF THE
MOUNTAINS.

SUNDAY WILL BE THE BEGINNING OF A WARMING TREND. THE WARMING
TREND WILL CONTINUE THROUGH AT LEAST WEDNESDAY AND POSSIBLY
THURSDAY DEPENDING ON HOW FAST THE NEXT TROUGH PUSHES INTO THE
REGION. AT THIS TIME LATE THURSDAY INTO FRIDAY LOOKS LIKE IT WILL
BE THE NEXT UNSETTLED PERIOD.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 323 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE WILL PRODUCE ANOTHER DAY OF RAIN AND SNOW
ACROSS THE REGION SATURDAY. THE UPPER LOW WILL EJECT INTO THE PLAINS
SATURDAY NIGHT WITH MOST PRECIPITATION ENDING SATURDAY EVENING.
ANOTHER SHOT SNOW POSSIBLE OVER THE HIGHER ELEVATIONS OF WYOMING
LATE SUNDAY INTO SUNDAY NIGHT.

WARMING TREND THROUGH MID WEEK WITH DRY CONDITIONS MONDAY THROUGH
WEDNESDAY...THEN ANOTHER SYSTEM MAY MOVE ACROSS THE AREA LATE NEXT
WEEK. NO FIRE CONCERNS THIS UPCOMING WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.

&&

$$

SHORT TERM...CLH
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...SML



  [top]

000
FXUS65 KRIW 172123
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
323 PM MDT FRI APR 17 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW. NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY WITH
WIDESPREAD LOW CLOUDS. MOUNTAIN AREAS ABOVE 7500 FEET WILL HAVE THE
BEST CHANCE FOR SNOW ACCUMULATION WITH AREAS RECEIVING UP TO 6
INCHES OF SNOW...ESPECAILLY ON CASPER MOUNTAIN AND THE SOUTHEAST
WIND RIVER MOUNTAINS AROUND SOUTH PASS.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.
TEMPERATURES WILL BE WARMING OVERALL.  CLOUDS WILL INCREASE
THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. AREAS OF HEAVIER PRECIPITATION WILL OCCUR
OVER THE HIGHER MOUNTAINS. SMALL HAIL AND STRONG WIND GUSTS WILL
ACCOMPANY THE THUNDERSTORMS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A SHORT WAVE DROPPING SOUTHEAST FROM FROM CANADA WILL FINALLY KICK
OUR RESIDENT CLOSED LOW OUT INTO THE PLAINS. THIS SYSTEM WILL
ENCOURAGE SOME SHOWER DEVELOPMENT ACROSS THE FORECAST AREA TO REMAIN
INTO THE EARLY EVENING ON SATURDAY. THE MID LEVEL COLD POOL MOVES IN
LATE IN THE NIGHT...LIKELY KEEPING A FEW SHOWERS GOING THORUGH
SUNDAY MORNING. THE GUSTY NORTH WINDS BEHIND THE COLD FRONT WILL
ALSO BEGIN TO TAPER OFF ON SUNDAY...WITH PERHAPS A FEW GUSTY
NORTHWEST WINDS REMAINING IN NORTHERN JOHNSON COUNTY SUNDAY
AFTERNOON.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. OVERALL THE FORECAST LOOKS RATHER MESSY...COOL AND
UNSETTLED WITH SIGNIFICANT DIFFERENCES IN THE MODEL SOLUTIONS FROM
RUN TO RUN AND BETWEEN ONE ANOTHER REGARDING THE NEXT SYSTEM. WAS
PRETTY GENEROUS WITH THE SLIGHT CHANCE POPS LATE IN THE PERIOD AS
BOTH GLOBAL MODELS BRING SOMETHING THROUGH AND KEEP IT AROUND FOR
A WHILE.

&&

.AVIATION.../00Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY
REDUCED IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY
REDUCED IN -SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN
END OF THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS
LINE THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.  IN THE AFTERNOON CONVECTION WILL DEVELOP OVER
THE WESTERN AND NORTHERN MOUNTAINS WITH INCREASING RAIN AND SNOW
SHOWERS AND ISOLATED THUNDERSTORMS WITH SMALL HAIL AND GUSTY
WINDS.  IN THE HEAVIER SHOWERS...LOCAL IFR CONDITIONS WILL OBSCURE
THE HIGHER MOUNTAINS.

&&

.FIRE WEATHER...

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW.  NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY.
WITH WIDESPREAD LOW CLOUDS THE MIXING HEIGHTS WILL BE LOW WITH
POOR SMOKE DISPERSAL..ESPECIALLY IN AREAS OF PRECIPITATION.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.  CLOUDS
WILL INCREASE THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. TEMPERATURES WILL BE WARMER IN THE NORTH
AND WEST. MIXING HEIGHTS WILL INCREASE WITH THE CONVECTIVE LIFT
WITH GOOD SMOKE DISPERSAL OR BETTER EXPECTED IN THE AFTERNOON.
AREAS OF HEAVIER PRECIPITATION OVER THE HIGHER MOUNTAINS WILL LOCALLY
CAUSE LOWER MIXING HEIGHTS AND DEVELOPING POOR SMOKE DISPERSAL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER











000
FXUS65 KRIW 172123
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
323 PM MDT FRI APR 17 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW. NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY WITH
WIDESPREAD LOW CLOUDS. MOUNTAIN AREAS ABOVE 7500 FEET WILL HAVE THE
BEST CHANCE FOR SNOW ACCUMULATION WITH AREAS RECEIVING UP TO 6
INCHES OF SNOW...ESPECAILLY ON CASPER MOUNTAIN AND THE SOUTHEAST
WIND RIVER MOUNTAINS AROUND SOUTH PASS.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.
TEMPERATURES WILL BE WARMING OVERALL.  CLOUDS WILL INCREASE
THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. AREAS OF HEAVIER PRECIPITATION WILL OCCUR
OVER THE HIGHER MOUNTAINS. SMALL HAIL AND STRONG WIND GUSTS WILL
ACCOMPANY THE THUNDERSTORMS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A SHORT WAVE DROPPING SOUTHEAST FROM FROM CANADA WILL FINALLY KICK
OUR RESIDENT CLOSED LOW OUT INTO THE PLAINS. THIS SYSTEM WILL
ENCOURAGE SOME SHOWER DEVELOPMENT ACROSS THE FORECAST AREA TO REMAIN
INTO THE EARLY EVENING ON SATURDAY. THE MID LEVEL COLD POOL MOVES IN
LATE IN THE NIGHT...LIKELY KEEPING A FEW SHOWERS GOING THORUGH
SUNDAY MORNING. THE GUSTY NORTH WINDS BEHIND THE COLD FRONT WILL
ALSO BEGIN TO TAPER OFF ON SUNDAY...WITH PERHAPS A FEW GUSTY
NORTHWEST WINDS REMAINING IN NORTHERN JOHNSON COUNTY SUNDAY
AFTERNOON.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. OVERALL THE FORECAST LOOKS RATHER MESSY...COOL AND
UNSETTLED WITH SIGNIFICANT DIFFERENCES IN THE MODEL SOLUTIONS FROM
RUN TO RUN AND BETWEEN ONE ANOTHER REGARDING THE NEXT SYSTEM. WAS
PRETTY GENEROUS WITH THE SLIGHT CHANCE POPS LATE IN THE PERIOD AS
BOTH GLOBAL MODELS BRING SOMETHING THROUGH AND KEEP IT AROUND FOR
A WHILE.

&&

.AVIATION.../00Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY
REDUCED IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY
REDUCED IN -SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN
END OF THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS
LINE THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.  IN THE AFTERNOON CONVECTION WILL DEVELOP OVER
THE WESTERN AND NORTHERN MOUNTAINS WITH INCREASING RAIN AND SNOW
SHOWERS AND ISOLATED THUNDERSTORMS WITH SMALL HAIL AND GUSTY
WINDS.  IN THE HEAVIER SHOWERS...LOCAL IFR CONDITIONS WILL OBSCURE
THE HIGHER MOUNTAINS.

&&

.FIRE WEATHER...

THE SOUTH AND EAST WILL BE COLD WITH WIDESPREAD SHOWERS OF RAIN
AND SNOW.  NORTHEAST WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY.
WITH WIDESPREAD LOW CLOUDS THE MIXING HEIGHTS WILL BE LOW WITH
POOR SMOKE DISPERSAL..ESPECIALLY IN AREAS OF PRECIPITATION.

A PACIFIC TROUGH WILL APPROACH THE WEST THROUGH THE AFTERNOON WITH
CONVECTION DEVELOPING OVER THE WEST AND NORTH MOUNTAINS.  CLOUDS
WILL INCREASE THROUGH THE MORNING WITH AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING. TEMPERATURES WILL BE WARMER IN THE NORTH
AND WEST. MIXING HEIGHTS WILL INCREASE WITH THE CONVECTIVE LIFT
WITH GOOD SMOKE DISPERSAL OR BETTER EXPECTED IN THE AFTERNOON.
AREAS OF HEAVIER PRECIPITATION OVER THE HIGHER MOUNTAINS WILL LOCALLY
CAUSE LOWER MIXING HEIGHTS AND DEVELOPING POOR SMOKE DISPERSAL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS63 KUNR 172046
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
246 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP WHERE THE BEST
RAINS OCCUR...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS
LATE.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...HELGESON




000
FXUS63 KUNR 172046
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
246 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. VFR CONDITIONS WILL
PREVAIL EARLY ON...BUT MVFR CIGS/VSBYS WILL DEVELOP WHERE THE BEST
RAINS OCCUR...ESPECIALLY LATE TONIGHT INTO SATURDAY. LOCAL IFR
CIGS/VSBYS EXPECTED OVER THE HIGHER TERRAIN OF THE BLACK HILLS
LATE.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...HELGESON



000
FXUS65 KCYS 171826
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1226 PM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...SML
FIRE WEATHER...CAH



000
FXUS65 KCYS 171826
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1226 PM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...SML
FIRE WEATHER...CAH




000
FXUS65 KCYS 171826
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1226 PM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...SML
FIRE WEATHER...CAH




000
FXUS65 KCYS 171826
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1226 PM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1223 PM MDT FRI APR 17 2015

UPPER LEVEL LOW PRESSURE OVER THE SOUTHWEST CONUS WILL MOVE
NORTHEASTWARD TONIGHT AND SATURDAY. WIDESPREAD MVFR TO IFR WILL
CONTINUE THROUGH TONIGHT AND INTO SATURDAY AS FOG...RAIN...AND
SNOW AFFECT THE REGION. MOST SNOW WILL BE FOUND ALONG AND WEST OF
THE LARAMIE RANGE WITH RAIN TO THE EAST. A FEW THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EARLY EVENING...MAINLY NEAR THE
INTERSTATE 80 CORRIDOR FROM ROUGHLY CHEYENNE TO SIDNEY.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 6 AM MDT SATURDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR WYZ103-105-
     106-110-112-118.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...SML
FIRE WEATHER...CAH



000
FXUS65 KRIW 171824
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1224 PM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LAND FALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

.AVIATION.../18Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY REDUCED
IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
-SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN END OF
THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS LINE
THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...HATTINGS







000
FXUS65 KRIW 171824
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1224 PM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LAND FALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

.AVIATION.../18Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY REDUCED
IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
-SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN END OF
THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS LINE
THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...HATTINGS






000
FXUS65 KRIW 171824
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1224 PM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LAND FALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

.AVIATION.../18Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY REDUCED
IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
-SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN END OF
THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS LINE
THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...HATTINGS







000
FXUS65 KRIW 171824
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1224 PM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LAND FALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

.AVIATION.../18Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO THROUGH FRIDAY. AREAS OF MVFR CEILINGS AND VISIBILITY REDUCED
IN -SHRASN...WITH LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
-SHRASN BR WILL CONTINUE TO ROTATE AROUND THE NORTHERN END OF
THIS SYSTEM MAINLY VICINITY AND SOUTH OF A KCPR- KLND-KRKS LINE
THROUGH THE PERIOD. TERMINALS NORTH OF THIS LINE WILL SEE
PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS THE NORTHERN
THIRD OF WYOMING.

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...HATTINGS






000
FXUS63 KUNR 171720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED AT 1118 AM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE SOUTHERN TWO THIRDS OF THE AREA THROUGH SATURDAY
MORNING. VFR CONDITIONS WILL PREVAIL EARLY ON...BUT MVFR
CIGS/VSBYS WILL DEVELOP WHERE THE BEST RAINS OCCUR...ESPECIALLY
LATE TONIGHT INTO SATURDAY. LOCAL IFR CIGS/VSBYS EXPECTED OVER THE
HIGHER TERRAIN OF THE BLACK HILLS LATE.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...HELGESON




000
FXUS63 KUNR 171720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED AT 1118 AM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE SOUTHERN TWO THIRDS OF THE AREA THROUGH SATURDAY
MORNING. VFR CONDITIONS WILL PREVAIL EARLY ON...BUT MVFR
CIGS/VSBYS WILL DEVELOP WHERE THE BEST RAINS OCCUR...ESPECIALLY
LATE TONIGHT INTO SATURDAY. LOCAL IFR CIGS/VSBYS EXPECTED OVER THE
HIGHER TERRAIN OF THE BLACK HILLS LATE.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...HELGESON



000
FXUS65 KCYS 171711
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1111 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.


&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH




000
FXUS65 KCYS 171711
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1111 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1052 AM MDT FRI APR 17 2015

A HIGH-IMPACT WINTER STORM CONTINUES THIS AM FOR THE INTERSTATE 80
CORRIDOR BETWEEN RAWLINS AND CHEYENNE. HIGH ELEVATION AREAS ALONG
THE SNOWY AND LARAMIE RANGES HAVE ALREADY RECEIVED ONE TO TWO FEET
OF SNOW. ROAD CLOSURES REMAIN IN EFFECT DUE TO EXTREMELY DANGEROUS
WINTER CONDITIONS AND NUMEROUS LARGE ACCIDENTS. NO DOUBT THAT HIGH
ELEVATIONS WILL CONTINUE TO SEE SNOW TODAY...BUT A RECENT ANALYSIS
OF DUAL POL CORRELATION COEFFICIENT SUGGESTS THE RAIN/SNOW LINE IS
RIGHT ON OUR DOOR STEP...BACKING SLOWLY WESTWARD WITH TIME. WE ARE
FIGHTING CONSIDERABLE WARM ADVECTION ALOFT WITH H7-H8 TEMPS LIKELY
TO RISE 1-2 DEG C THROUGH AFTN...BUT MODEST COLD AIR DAMMING ALONG
THE FRONT RANGE AND DYNAMIC COOLING WILL OFFSET THIS SOMEWHAT. WE
STILL THINK MODELS ARE A LITTLE TOO WARM...BUT WE SHOULD START TO
SEE SOME RAIN IN CHEYENNE SOON. AT MOST...EXPECT ANOTHER INCH OR
TWO OF SNOW ON THE WEST SIDE OF CHEYENNE WITH 4 TO 8 INCHES OVER
THE MOUNTAINS. ANY HEAVIER/INSTABILITY DRIVEN BANDS WILL LIKELY
FALL AS SNOW OVER LOWER ELEVATIONS JUST EAST OF THE FOOTHILLS.

SFC TEMPS ARE QUITE A BIT WARMER TO OUR EAST AND WE COULD START TO
SEE ADDITIONAL INSOLATION AS A MID LEVEL DRY SLOT WORKS INTO THAT
AREA THIS AFTERNOON. VISIBLE SATELLITE SHOWS THINNING STRATUS FROM
CHEYENNE TO SIDNEY. THIS WOULD SUPPORT MODELED CAPES AROUND 500
J/KG...SO COULD SEE SOME STRONG THUNDERSTORMS. ADDED SMALL HAIL
AND GUSTY WINDS TO THE GRIDS AFTER 21Z THIS AFTN.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.


&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

NE...NONE.
&&

$$

UPDATE...CLH
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH



000
FXUS63 KUNR 171630
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...JC




000
FXUS63 KUNR 171630
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 171630
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...JC




000
FXUS63 KUNR 171630
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 AM MDT FRI APR 17 2015

.UPDATE...
ISSUED AT 1022 AM MDT FRI APR 17 2015

UPPER LOW CONTINUES TO CHURN OVER THE FOUR CORNERS REGION WITH
BANDS OF LIGHT RAIN MOVING NORTHWEST THROUGH NEBRASKA AND JUST
EDGING INTO FAR SOUTHWEST SOUTH DAKOTA. EXPECT THESE BANDS OF
LIGHT RAIN TO CONTINUE TO MOVE INTO FAR SOUTHERN PORTIONS OF SOUTH
DAKOTA WITH RAIN EVENTUALLY MOVING NORTH TO THE INTERSTATE 90
CORRIDOR BY LATE THIS AFTERNOON.

MADE MINOR ADJUSTMENTS TO THE PROGRESSION OF RAIN NORTHWARD -
SLOWING IT DOWN...AND REMOVED MENTION OF ISOLATED THUNDER THROUGH
LATE AFTERNOON...AS IT LOOKS LIKE LAPSE RATES AND AVAILABLE ENERGY
ARE MEAGER AT BEST. BETTER CHANCES FOR THUNDER ACROSS NORTHEAST
WYOMING AND SOUTHERN SOUTH DAKOTA SATURDAY AFTERNOON.

REMAINDER OF FORECAST IN GOOD SHAPE. UPDATES ARE OUT.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...15
SHORT TERM...26
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 171142
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
542 AM MDT FRI APR 17 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...26
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 171142
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
542 AM MDT FRI APR 17 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...26
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 171142
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
542 AM MDT FRI APR 17 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 538 AM MDT FRI APR 17 2015

VFR CONDS WILL PREVAIL MOST PLACES IN THE PERIOD. A SLOW MOVING
UPPER LOW WILL SLIDE NE AND BRING MVFR CONDS IN RAIN TO MAINLY
EXTREME SW SD TODAY. MVFR CONDS WILL SPREAD NORTH
TONIGHT...AFFECTING THE RAP TERMINAL BY LATE IN THE PERIOD...WITH
SCT IFR CIGS POSSIBLE IN THE BLACK HILLS.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...26
LONG TERM...JC
AVIATION...JC




000
FXUS65 KCYS 171017
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
417 AM MDT FRI APR 17 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

     WINTER STORM WARNING UNTIL 3 PM MDT THIS AFTERNOON FOR WYZ118.

NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH




000
FXUS65 KCYS 171017
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
417 AM MDT FRI APR 17 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

     WINTER STORM WARNING UNTIL 3 PM MDT THIS AFTERNOON FOR WYZ118.

NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH



000
FXUS65 KCYS 171017
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
417 AM MDT FRI APR 17 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

     WINTER STORM WARNING UNTIL 3 PM MDT THIS AFTERNOON FOR WYZ118.

NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH




000
FXUS65 KCYS 171017
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
417 AM MDT FRI APR 17 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 415 AM MDT FRI APR 17 2015

CLOSED LOW OVR THE FOUR CORNERS IS FINALLY BEGINNING TO EVER SO
SLOWLY WOBBLE TO THE NORTHEAST TOWARDS COLORADO THIS MORNING. IT
WILL BE SLOW IN DOING SO...ONLY REACHING BETWEEN SALIDA/COLORADO
SPRINGS BY MIDNIGHT TONIGHT. THE WCB HAS BEEN EFFICIENT IN
ADVECTING MOISTURE THUS FAR...THOUGH PRECIP/SNOW RATES HAVE BEEN
TEMPERED SOMEWHAT BY DRY SLOT EXTENDING AND LIFTING NORTH ALONG
THE FRONT RANGE. MAIN FORECAST CHALLENGE CONTINUES TO BE THE
TIMING AND INTENSITY OF ADDL SNOW BANDS...IN ADDITION TO JUST HOW
MUCH THE AREA CAN WARM TODAY. OVERNIGHT TEMPS HAVE HOVERED AROUND
FREEZING BETWEEN 6-7 KFT WHICH HAS MITIGATED THE IMPACTS OF
FALLING SNOW ON AREA ROADWAYS AT LEAST IN THE CHEYENNE AREA...WITH
SOME MELTING OCCURRING UPON IMPACT. THIS CHANGES ABOVE 7 KFT WHERE
TEMPS HAVE BEEN IN THE UPPER 20S. MODELS HAVE BEEN DOING A FAIR
JOB OVERNIGHT...BUT CONTINUE TO BE MUCH TOO WARM WITH TEMPERATURE
PROGS. MODELS CONTINUE TO PROG THE NEXT VORT LOBE AND POCKET OF
ISENTROPIC LIFT TO ROTATE NORTH INTO THE AREA THIS MORNING. THIS
ALONG WITH THE PERSISTENT LLVL UPSLOPE WILL BE RESPONSIBLE FOR
BRINGING ADDL SNOWFALL TO THE AREA. THE ONE FLY IN THE OINTMENT IS
THE POTENTIAL IMPACT THAT THE DRY SLOT MAY HAVE THIS MORNING.
THIS ALONG WITH THUNDERSTORM COMPLEX OVR THE SRN PLAINS MAY ROB
SOME OF THE AVAILABLE MOISTURE. AT ANY RATE...CONFIDENCE REMAINS
HIGH THAT ADDL SNOW ACCUMULATIONS WILL OCCUR TODAY. SIMILAR TO
YESTERDAY...TEMPERATURES AND ALBEIT WEAK DAYTIME INSOLATION ARE
EXPECTED TO MITIGATE SOME OF THE IMPACTS AT LEAST IN THE VICINITY
OF CHEYENNE. THIS WILL BE DIFFERENT OVR THE HIER ELEVATIONS OVR
THE SUMMIT HOWEVER WHERE COLDER TEMPS WILL PERSIST. AS FOR
HEADLINES...HAVE OPTED TO EXTEND CENTRAL LARAMIE COUNTY UNTIL 3 PM
AND THE LARAMIE RANGE...LARAMIE VALLEY AND SNOWY RANGE UNTIL
MIDNIGHT TONIGHT. SNOW WILL FALL TONIGHT AS WELL...THOUGH RATES
SHOULD BE MUCH LESS. HIGHS TODAY WILL REACH THE MID/UPPER 30S AT
CHEYENNE AND LARAMIE WITH 40S AND 50S ELSEWHERE.

THE UPPER LOW WILL REACH THE CENTRAL PLAINS LATE SATURDAY...
ALTHOUGH MOISTURE CYCLING AROUND ITS PERIPHERY WILL CONTINUE TO
PRODUCE PRECIPITATION CHANCES. FORTUNATELY...TEMPERATURES WILL BE
WARMER ON SATURDAY LIMITING SNOW CHANCES TO ONLY THE HIGHEST
ELEVATIONS. HIGHS WILL RETURN TO THE 40S AND 50S EVERYWHERE FOR
SATURDAY.

MODELS PROG WEAK INSTABILITY OVR THE WRN NEBRASKA PANHANDLE TODAY
AND SATURDAY AFTERNOON. SO HAVE ADDED THUNDER MENTION TO THESE
AREAS AS A RESULT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 415 AM MDT FRI APR 17 2015

SUNDAY...CONTINUED COOL WITH NORTH NORTHWEST FLOW ALOFT
RETARDING HEATING...AND WINDY WITH DEEP UNIDIRECTIONAL NORTH
NORTHWEST WINDS AT LOW AND MID LEVELS AND PROGGED GRADIENTS. MAY BE
SOME OROGRAPHIC TYPE SNOWS PRIMARILY ALONG AND WEST OF INTERSTATE
25...OVER AND NEAR OUR SNOWY...SIERRA MADRE AND LARAMIE RANGES.

MONDAY...ISOLATED SNOW SHOWERS OVER OUR SNOWY AND SIERRA MADRE
RANGES IN NORTH NORTHWEST FLOW ALOFT...OTHERWISE DRY. SLOW WARMING
TREND TEMPERED BY NORTH NORTHWEST FLOW ALOFT.

TUESDAY...WARMING TREND BEGINS IN EARNEST AS THE FLOW ALOFT BACKS TO
NORTHWEST...HEIGHTS ALOFT RISE WITH THE APPROACH OF THE RIDGE ALOFT
OVER THE GREAT BASIN STATES.

WEDNESDAY...CONTINUED MILD AS THE RIDGE ALOFT MOVES OVERHEAD THOUGH
TEMPERATURES STILL LIMITED SOMEWHAT BY LOW LEVEL WINDS REMAINING
FROM AN UPSLOPE COMPONENT EAST OF THE LARAMIE RANGE.

THURSDAY...SLIGHTLY COOLER WITH MORE CLOUD COVER. BOTH THE 17/00Z
GFS AND ECMWF SHOW WIDESPREAD PRECIPITATION AND QPF OVER OUR
COUNTIES...WHICH IS QUITE LIKELY OVERDONE BASED ON THE SYNOPTIC
PATTERN...SO WILL BLEND WITH OUR NEIGHBORS AND KEEP LOW END POPS
GOING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 415 AM MDT FRI APR 17 2015

MOUNTAINS OBSCURED. IN SNOW...RAIN AND FOG...WIDESPREAD
IFR AND OCCASIONAL MVFR AT RAWLINS...LARAMIE...CHEYENNE AND
SIDNEY...WITH VFR AND MVFR PREVAILING AT CHADRON...ALLIANCE AND
SCOTTSBLUFF.

&&

.FIRE WEATHER...
ISSUED AT 415 AM MDT FRI APR 17 2015

WIDESPREAD MOISTURE AND COOLER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL MIDNIGHT MDT TONIGHT FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ103-
     105-106-110-112.

     WINTER STORM WARNING UNTIL 3 PM MDT THIS AFTERNOON FOR WYZ118.

NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...GCC
FIRE WEATHER...CAH



000
FXUS63 KUNR 170952
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
352 AM MDT FRI APR 17 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 352 AM MDT FRI APR 17 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE OKLAHOMA
PANHANDLE AREA RIGHT NOW...WITH WEAK HIGH PRESSURE OVER EASTERN MT
INTO WESTERN ND. UPPER LEVEL ANALYSIS SHOWS LARGE LOW PRESSURE
SYSTEM CENTERED OVER THE FOUR CORNERS AREA...WITH STRONG JET
WRAPPING AROUND THE SOUTHERN AND EASTERN SIDES OF THE LOW. CLOUD
SHIELD TO THE NORTH AND EAST OF THE SYSTEM IS PUSHING NORTHWARD
INTO SOUTHERN PARTS OF THE CWA...BUT DRYING UP AS IT MOVES INTO
VERY DRY AIRMASS OVER NORTHERN PORTIONS OF THE NORTHERN PLAINS
RIGHT NOW. REGIONAL RADARS SHOWING SHOWERS MOVING WEST-NORTHWEST
ACROSS MUCH OF WESTERN NEB INTO SOUTHEAST WY...WITH DRY CONDITIONS
PREVAILING ACROSS OUR CWA AT THE MOMENT. TEMPS CURRENTLY RANGE
FROM THE LOW TO MID 30S ACROSS PORTIONS OF NORTHEAST WY...THE
BLACK HILLS...AND FAR NORTHWEST SD...TO THE UPPER 40S ACROSS SOUTH
CENTRAL SD. WINDS ARE VARIABLE AT LESS THAN 10 MPH.

THE SYSTEM OVER THE FOUR CORNERS AREA EARLY THIS MORNING WILL MOVE
SLOWLY NORTHEASTWARD ACROSS SOUTHERN AND EASTERN CO OVER THE NEXT
COUPLE OF DAYS AND THEN ACCELERATE EASTWARD ACROSS THE CENTRAL
PLAINS SATURDAY NIGHT INTO SUNDAY. THE EXACT TRACK AND TIMING OF THE
SYSTEM IS STILL UNCERTAIN AT THIS POINT AND WILL ULTIMATELY HELP
DETERMINE HOW MUCH PCPN WE GET ACROSS THE AREA...ESPECIALLY NORTHERN
AND WESTERN PORTIONS OF THE CWA...WHERE AMOUNTS OF VERY LITTLE TO A
HALF INCH OR MORE ARE POSSIBLE DEPENDING ON THE TRACK. ALL THE 00Z
SHORT RANGE MODELS SHOW MOST OR ALL OF THE CWA RECEIVING AT LEAST A
LITTLE BIT OF RAINFALL...WITH THE HIGHEST AMOUNTS GENERALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD. THE 00Z GFS SHOWS THE HEAVIEST PCPN
FURTHER EAST TOWARD CENTRAL SD...WHILE THE OTHER MODELS GENERALLY
HAVE IT OVER FAR SOUTHWEST/SOUTHERN SD. WILL LEAN THE FORECAST MORE
TOWARD THE CONSENSUS AT THIS POINT AND KEEP HEAVIER PCPN AMOUNTS
OVER FAR SOUTHERN SD. FORECAST CONFIDENCE IS HIGHEST RIGHT NOW ON
SOUTHERN PORTIONS OF THE CWA RECEIVING THE MOST RAINFALL...AS WELL
AS THE BEST CHANCES FOR RAINFALL ACROSS THE CWA BEING LATER TONIGHT
INTO SATURDAY EVENING. PROJECTED RAINFALL AMOUNTS ACROSS THE CWA
WILL MOSTLY BE IN THE 0.25 TO 0.75 INCH RANGE...WITH LESSER AMOUNTS
LIKELY OVER FAR NORTHWESTERN PORTIONS OF THE CWA AND POSSIBLY AN
INCH OR MORE OVER FAR SOUTHWEST INTO SOUTH CENTRAL SD.
HOWEVER...WOULD TEND TO LEAN MORE TOWARD THE LIGHTER AMOUNTS FOR
MOST AREAS AS HAS BEEN THE CASE FOR SYSTEMS OF LATE.

FOR TODAY...SKIES WILL STAY MOSTLY CLOUDY ACROSS FAR SOUTHERN
PORTIONS OF THE CWA...WITH CLOUDS GRADUALLY INCREASING TO THE NORTH.
WITH MORE SUNSHINE...TEMPS THIS AFTERNOON WILL BE HIGHEST OVER FAR
NORTHERN AND EASTERN PORTIONS OF THE CWA...WITH HIGHS RANGING FROM
THE 50S OVER THE BLACK HILLS AND FAR SOUTHWEST SD TO THE MID TO
UPPER 60S OVER FAR NORTHWEST INTO CENTRAL SD. WINDS WILL BECOME EAST
TO NORTHEAST IN MOST AREAS BY THE AFTERNOON. CHANCES FOR SHOWERS
WILL MAINLY BE CONFINED TO SOUTHERN SD TODAY...WITH THE BEST CHANCES
IN THE AFTERNOON. CAN NOT RULE OUT A THUNDERSTORM OR TWO ACROSS
SOUTHERN AREAS AS WELL THIS AFTERNOON.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT AND SATURDAY...LOW LEVEL
MOISTURE AND UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE
NORTHERN PLAINS...ESPECIALLY LATER TONIGHT AND SATURDAY. SHOWERS AND
ISOLATED THUNDERSTORMS CAN BE EXPECTED ACROSS THE AREA. THE MOST
WIDESPREAD COVERAGE OF SHOWERS SHOULD BE ON SATURDAY...SO WILL GO
WITH LIKELY POPS ACROSS MOST OF THE CWA. WITH THE LOW STAYING FAR
ENOUGH SOUTH OF THE CWA...TEMPS WILL STAY WARM ENOUGH FOR MOSTLY
RAIN ACROSS EVEN THE BLACK HILLS...BUT COULD SEE A MIX OVER THE
HIGHEST ELEVATIONS...MAINLY LATE TONIGHT/EARLY SATURDAY AND THEN
SATURDAY NIGHT WHEN THE SYSTEM EXITS. A COLD FRONT WILL TRACK ACROSS
THE CWA LATE SATURDAY AND SATURDAY NIGHT...HELPING TO PUSH THE
SYSTEM OUT OF THE REGION...BUT WILL BRING GUSTY WINDS ACROSS THE
AREA INTO SUNDAY.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 352 AM MDT FRI APR 17 2015

BLOCKED FLOW TO DEVELOP OVER THE WESTERN ATLANTIC AND
EASTERN NOAM...WHICH WILL SET THE STAGE FOR WESTERN NOAM RIDING AND
POTENTIAL REX TYPE BLOCKING OVER THE WESTERN CONUS. THIS WILL
SUPPORT A LOW CONFIDENCE FLOW REGIME AS FORECAST MODELS WILL
CONTINUALLY ADJUST TO THE LATEST OBS GIVEN TYPICAL POOR MODEL
PERFORMANCE IN THESE PATTERNS. GENERALLY DRY CONDS CAN BE EXPECTED
GIVEN THE REGION/S PROXY TO THE EASTERN NOAM UPPER TROUGH. A WEAK
SIGNAL FOR PRECIP DOES REMAIN TOWARD THE END OF THE PERIOD WHEN
FORECAST MODELS TRY TO ADVECT A WANDERING UPPER TROUGH EAST.
HOWEVER...AS ALREADY STATED...LOW CONFIDENCE PER FLOW DETAILS LENDS
ONLY A 20 POP AT BEST...WITH DRY THE LIKELY SCENARIO GIVEN THE
PATTERN. GIVEN STRONG INFLUENCE EXPECTED OF THE EVENTUAL EASTERN
CONUS UPPER LOW...EXPECT TEMPS TO BE NEAR OR SLIGHTLY BELOW SEASONAL
NORMS IN THE MAJORITY OF THE PERIOD.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 352 AM MDT FRI APR 17 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE
EXCEPTION TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR
CIGS IN THE AFTERNOON.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...26
LONG TERM...JC
AVIATION...JC



000
FXUS65 KRIW 170908
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
308 AM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LANDFALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

&&

.AVIATION.../12Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLATED IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VICINITY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.
&&

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...AEM
FIRE WEATHER...HATTINGS









000
FXUS65 KRIW 170908
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
308 AM MDT FRI APR 17 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

ANOTHER DAY HAS ARRIVED AND IT IS ANOTHER DAY IN DEALING WITH ONE OF
THE MOST FICKLE FEATURES IN WEATHER FORECASTING...THAT UPPER LEVEL
LOW THAT IS NOW SPINNING OVER SOUTHERN COLORADO. ANOTHER SPOKE OF
ENERGY HAS ROTATED INTO SOUTHEASTERN WYOMING BUT FOR NOW IS STAYING
OUT OF OUR COUNTY WARNING AREA. SEEING THE CHEYENNE RADAR...IT
ALMOST MAKES ME THINK I AM BACK IN MY ALMA MATER STATE OF NORTH
CAROLINA RATHER THAN WYOMING AS IT ALMOST LOOKS LIKE A SPIRAL BAND
FROM A LANDFALLING HURRICANE. SO FAR THE MOVEMENT HAS BEEN MORE
WEST THAN NORTH...SO THE BEST CHANCE OF SEEING EFFECTS FROM IT
WOULD BE ACROSS EASTERN SWEETWATER COUNTY...SO THE HIGHEST POPS
WERE PUT THERE. LIKE YESTERDAY...THE MILLION DOLLAR QUESTION IS
HOW FAR NORTH AND WEST WILL THE PRECIPITATION GET. THE GFS BRINGS
IT FURTHER NORTH TO AROUND KAYCEE TO RIVERTON LINE WHILE THE NAM
IS SLIGHTLY FURTHER SOUTH. CONTINUITY HANDLED THIS FAIRLY WELL SO
WE MADE FEW CHANGES...BUT THE EXACT NORTHERN EDGE IS IMPOSSIBLE TO
PREDICT AT THIS TIME. THE AIR IS STILL FAIRLY WARM WITH 700
MILLIBAR TEMPERATURES AROUND MINUS 2 SO SNOW LEVELS WOULD LIKELY
BE MAINLY ABOVE 7500 FEET. AND EVEN HERE...SINCE MOST OF ANY SNOW
WILL FALL DURING THE DAY IT WOULD MELT ON ROADS WITH THE STRONG
APRIL SUN...SO WE WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME.
MEANWHILE...IT WILL BE A TALE OF TWO AREAS WITH THE NORTHWEST HALF
OF THE AREA HAVING A FAIRLY NICE DAY WITH SOME SUNSHINE AND NEAR
NORMAL TEMPERATURES. THE MODELS HAVE THE SAME DISAGREEMENT WITH
THE PRECIPITATION PATTERN TONIGHT BUT BOTH THE NAM AND GFS KEEP
THE LIONS SHARE OF THE QPF EAST OF THE RIVERTON COUNTY WARNING
AREA.

FINALLY ON SATURDAY...A COLD FRONT AND KICKER TROUGH WILL MOVE IN
FROM THE NORTHWEST AND FINALLY GIVE THE UPPER LEVEL LOW A BOOT TO
THE NORTH AND EAST. JUST ABOUT EVERYONE WILL HAVE A CHANCE FOR
SHOWERS ONCE AGAIN AS THE FRONT DROPS SOUTHWARD. THE MODELS ARE ALSO
SHOWING A HEAVIER BAND OF PRECIPITATION WITH SOME CONVERGENCE AS THE
FRONT DROPS SOUTHWARD. AGAIN...BOTH THE MODELS KEEP THIS FEATURE
JUST EAST OF OUR AREA BUT WE DID ADJUST POPS UPWARD IN EASTERN
NATRONA AND JOHNSON COUNTY IN CASE OF A SHIFT TO THE EAST.

COOLER AIR THEN MOVES IN BEHIND THE FRONT FOR SATURDAY NIGHT AND
SUNDAY. THE MODELS ONCE AGAIN ARE IN SOMEWHAT OF A DISAGREEMENT. THE
GFS KEEPS SOME ENERGY OVER THE AREA WITH SHOWERS CONTINUING ACROSS
MUCH OF THE AREA...ESPECIALLY ACROSS THE SOUTHWEST. MEANWHILE...THE
NAM IS DRIER WITH KICKING THE ENERGY FURTHER TO THE EAST AND HAVING
ONLY SPOTTY MOUNTAIN SHOWERS. THIS FAR OUT...WE TWEAKED POPS AND QPF
DOWN JUST A BIT BUT WILL NOT MAKE SWEEPING CHANGES UNTIL THE MODELS
COME INTO BETTER AGREEMENT.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT

A NORTHWEST FLOW PATTERN REMAINS IN THE FORECAST TO BEGIN THE WORK
WEEK NEXT WEEK. THE UPPER LEVEL LOW THAT WE`VE BEEN TRACKING IN
PREVIOUS DISCUSSIONS...WILL PROGRESS EASTWARD OVER THE GREAT LAKES
THROUGH WEDNESDAY...PER THE 00Z GFS/ECMWF RUNS. THIS WILL ALLOW A
SHORT WAVE RIDGE TO MOVE OVER THE NORTHERN AND CENTRAL ROCKIES
THROUGH 00Z THURSDAY.

THE GFS CONTINUES TO BE THE MORE PROGRESSIVE MODEL DIGGING A LONG
WAVE TROUGH OVER THE WESTERN CONUS...WHILE THE ECMWF RESOLVES A CUT
OFF LOW DIGGING SOUTHWARD ALONG THE CALIFORNIA COAST WEDNESDAY AND
THURSDAY. IT THEN REINFORCES THIS LOW WITH A DIGGING TROUGH FROM THE
GULF OF ALASKA AND BEGINS TO MERGE THESE TWO FEATURES OVER THE GREAT
BASIN BY THE END OF THE FORECAST PERIOD. AS A RESULT...THE GFS
CONTINUES TO SPEW SHORT WAVES FROM THE SOUTHWEST OVER THE FORECAST
AREA. KEPT A SLIGHT CHANCE TO CHANCE OF MAINLY RAIN SHOWERS FROM
WEDNESDAY AFTERNOON ONWARD. A RAIN/SNOW MIX TO SNOW SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS.

&&

.AVIATION.../12Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLATED IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VICINITY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.
&&

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE...AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS
SOME RAIN AND SNOW SHOWERS OVER THE AREA THROUGH TODAY. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES
ALONG WITH LOWER HUMIDITY...BUT REMAINING ABOVE CRITICAL LEVELS. A
COLD FRONT WILL DROP SOUTHWARD ACROSS THE AREA SATURDAY WITH A
CHANCE OF SHOWERS FOR MOST AREAS FOLLOWED BY COOL DOWN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...AEM
FIRE WEATHER...HATTINGS








000
FXUS65 KRIW 170554
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 PM MDT THU APR 16 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH FRIDAY (ISSUED AT 247 PM MDT)

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLD IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VCNTY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER













000
FXUS65 KRIW 170554
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 PM MDT THU APR 16 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH FRIDAY (ISSUED AT 247 PM MDT)

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLD IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VCNTY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER












000
FXUS65 KRIW 170554
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 PM MDT THU APR 16 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH FRIDAY (ISSUED AT 247 PM MDT)

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLD IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VCNTY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER













000
FXUS65 KRIW 170554
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 PM MDT THU APR 16 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH FRIDAY (ISSUED AT 247 PM MDT)

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DRIFT ACROSS SOUTHERN
COLORADO ON FRIDAY.  SCT MVFR...ISOLD IFR -SHRA/-SHSN WILL CONTINUE
TO ROTATE AROUND THE NORTHERN END OF THIS SYSTEM MAINLY VCNTY AND
SOUTH OF A KCPR-KRKS LINE THROUGH THE PERIOD.  TERMINALS NORTH OF
THIS LINE WILL SEE PREVAILING VFR CONDITIONS WITH MAINLY SKC ACROSS
THE NORTHERN THIRD OF WYOMING.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER












000
FXUS63 KUNR 170500
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1100 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1059 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS ON FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS63 KUNR 170500
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1100 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1059 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS ON FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS65 KCYS 170453
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1053 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 539 PM MDT THU APR 16 2015

LATEST RADAR TRENDS SHOWING PRECIP FILLING IN OVER NORTEASTERN
COLORADO. LATEST INFRARED IMAGERY SHOWING RAPIDLY COOLING CLOUD
TOPS OVER SOUTHEASTERN COLORADO...MOVING DUE NORTH...SO OUR DRY
SLOT WE HAVE BEEN LOOKING AT LATE THIS AFTERNOON IS GETTING EDGED
EASTWARD. BOTH GFS AND NAM SOUNDINGS SHOWING FAVORABLE TEMPERATURE
PROFILES LATE THIS EVENING WITH SURFACE TEMPERATURES FALLING TO
BELOW FREEZING DURING THE BEST TIME OF LOW LEVEL MOISTURE
CONVERGENCE OVER THE SOUTH LARAMIE RANGE. VERY STRONG ISENTROPIC
LIFT OVER EXTREME SOUTHEAST WYOMING THIS EVENING FROM THE 300-310K
PRESSURE SURFACES. OPTED TO UPGRADE THE CURRENT WINTERWEATHER
ADVISORY WE HAVE GOING FOR CENTRAL LARAMIE COUNTY TO A WINTER
STORM WARNING AS WELL AS INCREASING SNOW AMOUNTS ACROSS THE WARNED
AREA AS ALL GUIDANCE POINTING TOWARDS OVER AN INCH OF STORM TOTAL
QPF WITH THIS EVENT. UPDATES HAVE BEEN SENT.

NEXT CONCERN DEALS WITH POSSIBILITY OF UPGRADING ADVISORIES
FURTHER NORTH ACROSS THE CENTRAL LARAMIE RANGE AND POSSIBLY PLATTE
COUNTY. CURRENT THINKING RIGHT NOW IS THE AXIS OF HEAVIEST PRECIP
WILL MOVE INTO THIS AREA TOMORROW AFTERNOON DURING DAYLIGHT
HOURS...SO MAYBE THERE WOULD BE A LITTLE MORE MELTING. DECIDED TO
LET THE NIGHT CREW TAKE ANOTHER LOOK AT THIS BEFORE ISSUING
ANYTHING.

&&

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1049 PM MDT THU APR 16 2015

HRRR GUIDANCE USED FOR THE 06Z TAFS. IFR.LIFR CONDITIONS INITIALLY
CONFINED TO KLAR AND KCYS WITH WRAP AROUND MOISTURE AND SNOW.
LATEST IR IMAGERY SHOWS COOLING CLOUD TOPS THAT INDICATES MOE
WIDESPREAD PRECIP LATER THIS MORNING. HRRR SHOWS IFR/LIFR
SPREADING EAST INTO THE SOUTHERN NEBRASKA PANHANDLE DURING THE
09-10Z TIMEFRAME AND CONTINUING THROUGH THE DAY FRIDAY. COULD
PERSIST THROUGH FRIDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110-112.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...RE
LONG TERM...CLH
AVIATION...GCC
FIRE WEATHER...RE



000
FXUS65 KCYS 170453
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1053 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 539 PM MDT THU APR 16 2015

LATEST RADAR TRENDS SHOWING PRECIP FILLING IN OVER NORTEASTERN
COLORADO. LATEST INFRARED IMAGERY SHOWING RAPIDLY COOLING CLOUD
TOPS OVER SOUTHEASTERN COLORADO...MOVING DUE NORTH...SO OUR DRY
SLOT WE HAVE BEEN LOOKING AT LATE THIS AFTERNOON IS GETTING EDGED
EASTWARD. BOTH GFS AND NAM SOUNDINGS SHOWING FAVORABLE TEMPERATURE
PROFILES LATE THIS EVENING WITH SURFACE TEMPERATURES FALLING TO
BELOW FREEZING DURING THE BEST TIME OF LOW LEVEL MOISTURE
CONVERGENCE OVER THE SOUTH LARAMIE RANGE. VERY STRONG ISENTROPIC
LIFT OVER EXTREME SOUTHEAST WYOMING THIS EVENING FROM THE 300-310K
PRESSURE SURFACES. OPTED TO UPGRADE THE CURRENT WINTERWEATHER
ADVISORY WE HAVE GOING FOR CENTRAL LARAMIE COUNTY TO A WINTER
STORM WARNING AS WELL AS INCREASING SNOW AMOUNTS ACROSS THE WARNED
AREA AS ALL GUIDANCE POINTING TOWARDS OVER AN INCH OF STORM TOTAL
QPF WITH THIS EVENT. UPDATES HAVE BEEN SENT.

NEXT CONCERN DEALS WITH POSSIBILITY OF UPGRADING ADVISORIES
FURTHER NORTH ACROSS THE CENTRAL LARAMIE RANGE AND POSSIBLY PLATTE
COUNTY. CURRENT THINKING RIGHT NOW IS THE AXIS OF HEAVIEST PRECIP
WILL MOVE INTO THIS AREA TOMORROW AFTERNOON DURING DAYLIGHT
HOURS...SO MAYBE THERE WOULD BE A LITTLE MORE MELTING. DECIDED TO
LET THE NIGHT CREW TAKE ANOTHER LOOK AT THIS BEFORE ISSUING
ANYTHING.

&&

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1049 PM MDT THU APR 16 2015

HRRR GUIDANCE USED FOR THE 06Z TAFS. IFR.LIFR CONDITIONS INITIALLY
CONFINED TO KLAR AND KCYS WITH WRAP AROUND MOISTURE AND SNOW.
LATEST IR IMAGERY SHOWS COOLING CLOUD TOPS THAT INDICATES MOE
WIDESPREAD PRECIP LATER THIS MORNING. HRRR SHOWS IFR/LIFR
SPREADING EAST INTO THE SOUTHERN NEBRASKA PANHANDLE DURING THE
09-10Z TIMEFRAME AND CONTINUING THROUGH THE DAY FRIDAY. COULD
PERSIST THROUGH FRIDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110-112.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...RE
LONG TERM...CLH
AVIATION...GCC
FIRE WEATHER...RE




000
FXUS63 KUNR 170228
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
828 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 170228
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
828 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 170228
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
828 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 170228
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
828 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 823 PM MDT THU APR 16 2015

HAVE REDUCED POPS FOR BOTH TONIGHT AND MUCH OF FRIDAY FOR ALL
AREAS EXCEPT FAR SRN SD. THE LATEST 00Z NAM AND OTHER SHORT RANGE
GUIDANCE CONTINUE THE TREND FROM THE 18Z GUIDANCE OF KEEPING THE
MAJORITY OF RAIN TO OUR SOUTH INTO TOMORROW AFTERNOON. HAVE ALSO
LOWERED CLOUD COVER TO FOLLOW SUIT. REST OF FCST LARGELY
UNCHANGED.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS65 KCYS 162352
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
552 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 539 PM MDT THU APR 16 2015

LATEST RADAR TRENDS SHOWING PRECIP FILLING IN OVER NORTEASTERN
COLORADO. LATEST INFRARED IMAGERY SHOWING RAPIDLY COOLING CLOUD
TOPS OVER SOUTHEASTERN COLORADO...MOVING DUE NORTH...SO OUR DRY
SLOT WE HAVE BEEN LOOKING AT LATE THIS AFTERNOON IS GETTING EDGED
EASTWARD. BOTH GFS AND NAM SOUNDINGS SHOWING FAVORABLE TEMPERATURE
PROFILES LATE THIS EVENING WITH SURFACE TEMPERATURES FALLING TO
BELOW FREEZING DURING THE BEST TIME OF LOW LEVEL MOISTURE
CONVERGENCE OVER THE SOUTH LARAMIE RANGE. VERY STRONG ISENTROPIC
LIFT OVER EXTREME SOUTHEAST WYOMING THIS EVENING FROM THE 300-310K
PRESSURE SURFACES. OPTED TO UPGRADE THE CURRENT WINTERWEATHER
ADVISORY WE HAVE GOING FOR CENTRAL LARAMIE COUNTY TO A WINTER
STORM WARNING AS WELL AS INCREASING SNOW AMOUNTS ACROSS THE WARNED
AREA AS ALL GUIDANCE POINTING TOWARDS OVER AN INCH OF STORM TOTAL
QPF WITH THIS EVENT. UPDATES HAVE BEEN SENT.

NEXT CONCERN DEALS WITH POSSIBILITY OF UPGRADING ADVISORIES
FURTHER NORTH ACROSS THE CENTRAL LARAMIE RANGE AND POSSIBLY PLATTE
COUNTY. CURRENT THINKING RIGHT NOW IS THE AXIS OF HEAVIEST PRECIP
WILL MOVE INTO THIS AREA TOMORROW AFTERNOON DURING DAYLIGHT
HOURS...SO MAYBE THERE WOULD BE A LITTLE MORE MELTING. DECIDED TO
LET THE NIGHT CREW TAKE ANOTHER LOOK AT THIS BEFORE ISSUING
ANYTHING.

&&

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 539 PM MDT THU APR 16 2015

IFR/LIFR CONDITIONS WILL PREVAIL FOR THE SOUTHEAST WYOMING TERMINALS
THROUGH THE TAF PERIOD. SNOWFALL RATES SHOULD DIMINISH OVER THE NEXT
FEW HOURS...BUT CIGS ARE LIKELY TO REMAIN VERY LOW OVERNIGHT AS LLVL
UPSLOPE DEVELOPS. ANOTHER ROUND OF VERY HEAVY PCPN SHOULD LIFT NORTH
ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE AFTER 09Z FRI...AND
WILL AFFECT THE AREA THROUGH AT LEAST 00Z SAT. HEAVY SNOW IS LIKELY
WITH VERY LOW VISIBILITIES UNDER A QUARTER MILE POSSIBLE. TEMPS ARE
EXPECTED TO BE WARM ENOUGH FOR RAIN ACROSS WESTERN NEB...SO MVFR TO
LOCALLY IFR CIGS/VSBYS ARE EXPECTED FOR THOSE TERMINALS.

&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110-112.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE



000
FXUS65 KCYS 162352
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
552 PM MDT THU APR 16 2015

.UPDATE...
ISSUED AT 539 PM MDT THU APR 16 2015

LATEST RADAR TRENDS SHOWING PRECIP FILLING IN OVER NORTEASTERN
COLORADO. LATEST INFRARED IMAGERY SHOWING RAPIDLY COOLING CLOUD
TOPS OVER SOUTHEASTERN COLORADO...MOVING DUE NORTH...SO OUR DRY
SLOT WE HAVE BEEN LOOKING AT LATE THIS AFTERNOON IS GETTING EDGED
EASTWARD. BOTH GFS AND NAM SOUNDINGS SHOWING FAVORABLE TEMPERATURE
PROFILES LATE THIS EVENING WITH SURFACE TEMPERATURES FALLING TO
BELOW FREEZING DURING THE BEST TIME OF LOW LEVEL MOISTURE
CONVERGENCE OVER THE SOUTH LARAMIE RANGE. VERY STRONG ISENTROPIC
LIFT OVER EXTREME SOUTHEAST WYOMING THIS EVENING FROM THE 300-310K
PRESSURE SURFACES. OPTED TO UPGRADE THE CURRENT WINTERWEATHER
ADVISORY WE HAVE GOING FOR CENTRAL LARAMIE COUNTY TO A WINTER
STORM WARNING AS WELL AS INCREASING SNOW AMOUNTS ACROSS THE WARNED
AREA AS ALL GUIDANCE POINTING TOWARDS OVER AN INCH OF STORM TOTAL
QPF WITH THIS EVENT. UPDATES HAVE BEEN SENT.

NEXT CONCERN DEALS WITH POSSIBILITY OF UPGRADING ADVISORIES
FURTHER NORTH ACROSS THE CENTRAL LARAMIE RANGE AND POSSIBLY PLATTE
COUNTY. CURRENT THINKING RIGHT NOW IS THE AXIS OF HEAVIEST PRECIP
WILL MOVE INTO THIS AREA TOMORROW AFTERNOON DURING DAYLIGHT
HOURS...SO MAYBE THERE WOULD BE A LITTLE MORE MELTING. DECIDED TO
LET THE NIGHT CREW TAKE ANOTHER LOOK AT THIS BEFORE ISSUING
ANYTHING.

&&

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 539 PM MDT THU APR 16 2015

IFR/LIFR CONDITIONS WILL PREVAIL FOR THE SOUTHEAST WYOMING TERMINALS
THROUGH THE TAF PERIOD. SNOWFALL RATES SHOULD DIMINISH OVER THE NEXT
FEW HOURS...BUT CIGS ARE LIKELY TO REMAIN VERY LOW OVERNIGHT AS LLVL
UPSLOPE DEVELOPS. ANOTHER ROUND OF VERY HEAVY PCPN SHOULD LIFT NORTH
ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE AFTER 09Z FRI...AND
WILL AFFECT THE AREA THROUGH AT LEAST 00Z SAT. HEAVY SNOW IS LIKELY
WITH VERY LOW VISIBILITIES UNDER A QUARTER MILE POSSIBLE. TEMPS ARE
EXPECTED TO BE WARM ENOUGH FOR RAIN ACROSS WESTERN NEB...SO MVFR TO
LOCALLY IFR CIGS/VSBYS ARE EXPECTED FOR THOSE TERMINALS.

&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110-112.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE




000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER









000
FXUS65 KRIW 162316
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAIN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER










000
FXUS63 KUNR 162252
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
452 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS63 KUNR 162252
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
452 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 162252
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
452 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON




000
FXUS63 KUNR 162252
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
452 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 452 PM MDT THU APR 16 2015

VFR CONDITIONS EXPECTED MOST AREAS THROUGH FRIDAY. THE EXCEPTION
TO THIS IS ACROSS FAR SRN SD WHERE RAIN MAY BRING MVFR CIGS LATE
TONIGHT INTO FRIDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...JOHNSON



000
FXUS65 KCYS 162050
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
250 PM MDT THU APR 16 2015

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.


&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110.

NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE




000
FXUS65 KCYS 162050
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
250 PM MDT THU APR 16 2015

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.


&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110.

NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE



000
FXUS65 KCYS 162050
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
250 PM MDT THU APR 16 2015

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.


&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110.

NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE




000
FXUS65 KCYS 162050
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
250 PM MDT THU APR 16 2015

.SHORT TERM...(TONIGHT-SATURDAY NIGHT)
ISSUED AT 248 PM MDT THU APR 16 2015

FORECAST PROBLEMS WILL BE TEMPERATURES AND PRECIPITATION AMOUNTS
AND WHERE THE HEAVIER SNOWS WILL FALL OVER THE NEXT COUPLE DAYS.

UPPER LOW SPINNING OVER THE 4 CORNERS AREA SHOULD BEGIN A SLOW ENE
DRIFT ACROSS COLORADO LATER TONIGHT BEFORE LIKELY STALLING AGAIN
OVER COLORADO. PERIODIC DISTURBANCES ROTATING AROUND THIS LOW WILL
BRING SHOTS OF RAIN AND SNOW TO MOST OF THE CWA THROUGH SATURDAY
BEFORE A SHORTWAVE DROPS OUT OF SW CANADA AND PICKS UP THE
LOW...MOVING IT EAST INTO KANSAS AND DECREASING PCPN ACROSS THE
CWA. HIGHEST SNOWFALL WILL BE OVER THE LARAMIE RANGE AND THE
SNOWYS. ONE CONCERN IS CONVECTION CURRENTLY FIRING OVER KANSAS
WHICH COULD CUT MOISTURE AVAILABILITY IN THIS AREA AND REDUCE
SNOWFALL AMOUNTS. CURRENT WINTER STORM WARNING LOOKS IN GOOD SHAPE
REGARDLESS BUT FOR AREAS SUCH AS AROUND CHEYENNE SNOWFALL COULD
TURN OUT GREATER THAN CURRENTLY ANTICIPATED...WITH THE GREATEST
RISK BEING LATER TONIGHT INTO FRIDAY MORNING. WILL STAY WITH THE
WINTER WX ADVY BUT IT WONT TAKE MUCH TO UPGRADE IT.

TEMPERATURES TRICKY THROUGH FRIDAY ESPECIALLY ADJACENT TO THE LAR
RANGE WHERE EXPECTED WARMING TODAY DID NOT OCCUR DUE TO SOME COLD
AIR DAMMING. SFC WINDS LIKELY TO REMAIN NORTH TO NORTHEASTERLY
THUS WAA WILL BE LIMITED IF AT ALL IN THIS AREA. THUS EXPECT PCPN
TO REMAIN ALL SNOW THUS HAVE UPPED SNOWFALL AMOUNTS THERE. SHOULD
SEE IMPROVEMENT FRIDAY AFTERNOON OVER THE HIGH PLAINS WITH THE
NEXT EXPECTED LULL. PCPN SHOULD BECOME MORE SHOWERY IN NATURE
FRIDAY NIGHT AND SATURDAY WITH SNOW LEVEL RISING SLOWLY AS SOME
WARMING OCCURS.

.LONG TERM...(SUNDAY-WEDNESDAY)
ISSUED AT 248 PM MDT THU APR 16 2015

OUR PROBLEM CHILD UPPER-LOW WILL FINALLY LOOSEN ITS GRIP ON SUN AS A
STRONG KICKER SYSTEM DIVES SOUTHEAST ACROSS THE DAKOTAS. THE PATTERN
WILL REMAIN UNSETTLED THOUGH AS CYCLONIC MID LEVEL FLOW WILL REMAIN
INTACT OVER THE NORTHERN/CENTRAL ROCKIES. EXPECT INSTABILITY SHOWERS
TO CONTINUE FOR MOST OF THE CWA LATE IN THE WEEKEND. GFS/ECMWF SHOW
H7 TEMPS FALLING TO AROUND -8 TO -10 DEG C ON SUN AM BEHIND A STRONG
COLD FROPA...SO EXPECT THE PTYPE TO BE SNOW. THIS SHOULD NOT AMOUNT
TO MUCH OUTSIDE OF THE MOUNTAINS THOUGH. MOST MEDIUM RANGE GUIDANCE
SHOWS THE COOL/MOIST CYCLONIC FLOW PERSISTING THROUGH THE MIDDLE OF
NEXT WEEK...SO EXPECT CONTINUED DAILY CHANCES FOR RAIN/SNOW SHOWERS
WITH LITTLE OR NO ACCUMULATIONS. A WARMING TREND SHOULD BEGIN BY WED
AS RIDGING FINALLY TRANSLATES EASTWARD...ALLOWING H7 TEMPS TO CLIMB
BACK ABOVE FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.


&&

.FIRE WEATHER...
ISSUED AT 248 PM MDT THU APR 16 2015

MINIMAL CONCERNS SEEN THROUGH THE WEEKEND WITH GENEROUS RAIN AN/OR
SNOWS FALLING OVER MUCH OF THE AREA. TEMPERATURES WILL BE COOL TO
MILD WITH WEATHER CONDITIONS NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ103-105-106-
     110.

NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RE



000
FXUS65 KRIW 162047
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER






000
FXUS65 KRIW 162047
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
247 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

THE SOUTH AND EAST WILL BE ON THE NORTHWEST QUADRANT OF A CUT OFF
LOW NOW OVER THE FOUR CORNERS AREA. WRAP AROUND MOISTURE WILL BRING
CLOUDS AND RAIN...RAN SNOW MIX AND MOUNTAIN SNOW TO MAINLY EASTERN
SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY. THE PRECIPITATION
SHOULD BE GENERALLY LIGHT AND PERIODIC WITH LITTLE ACCUMULATION IN
THE LOWER ELEVATIONS. WITH BREAKS IN THE MOUNTAIN SNOWFALL DO NOT
EXPECT ENOUGH IMPACT OVERALL FOR ADVISORIES ON CASPER MOUNTAIN OR
OVER THE GREEN AND RATTLESNAKE RANGES AS MELTING IS LIKELY TO
OCCUR DURING THE BREAKS IN THE SNOWFALL. STRONG NORTHEAST WINDS
ARE EXPECTED TO CONTINUE ACROSS THE SOUTH AND EAST...DECREASING TO
THE NORTH AND WEST. THE SOUTHEAST AREA WILL BE THE COLDEST...WHILE
TO THE NORTH AND WEST TEMPERATURES WILL WARM WITH CLEARING
EXPECTED.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AS THE UPPER LOW CONTINUES TO SPIN OVER COLORADO...IT WILL WRAP
SOME MORE MOISTURE AROUND THE LOW INTO EASTERN PORTIONS OF THE
FORECAST AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THE BAND OF
PRECIPITATION WILL REACH BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO POTENTIALLY AS FAR WEST AS FREMONT AND SWEETWATER
COUNTIES. THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE
NORTHERN STORM TRACK ALONG OUR BORDER WITH CANADA...THIS WILL
EVENTUALLY SWING DOWN ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED
LOW TO FINALLY MOVE ON INTO THE PLAINS. THIS KICKER SYSTEM COULD
ENCOURAGE SOME SHOWERS AS IT SWINGS ON THROUGH...WITH SOME SHOWERS
CONTINUING INTO SUNDAY AS THE COLD POOL ALOFT MOVES
OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE FOR ANOTHER DAY.

IT LOOKS LIKE THERE WILL BE A BIT OF A LULL EARLY NEXT WEEK INTO MID
WEEK AS A WEAK RIDGE TRIES TO BUILD IN AHEAD OF THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO DIG ALONG THE WEST COAST AND COME ASHORE
LATE NEXT WEEK. THERE STILL EXIST SOME SIGNIFICANT MODEL DIFFERENCES
WITH THE NEXT SYSTEM WHILE THE GFS BRINGS IN A DOUBLE BARREL LOW
INTO THE GREAT BASIN WHILE THE ECMWF SPLITS THE ENERGY...EITHER
WAY...IT LOOKS LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE
RECORDS NEXT WEEK AND WE COULD HAVE A FEW MORE CHANCES FOR SOME
PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

AREAS OF MVFR TO LOCAL IFR CEILINGS AND VISIBILITY REDUCED IN
LIGHT SNOW AND FOG WILL CONTINUE ACROSS NATRONA...SOUTHERN AND
EASTERN FREMONT AND SWEETWATER COUNTIES THROUGH 00Z SATURDAY.
NORTH AND WEST OF THIS AREA WILL BE PREVAILING VFR . LOCAL MVFR
CEILINGS AND VISIBILITY REDUCED IN FOG CAN BE EXPECTED ALONG
RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
00Z SATURDAY. GUSTY NE SURFACE WINDS AT 25-35KTS WITH GUSTS TO
40KTS WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY
KRKS.

&&

.FIRE WEATHER...

SNOW AND RAIN WILL CONTINUE ACROSS THE SOUTH AND EAST WITH CLEARING
NORTH AND WEST.  SWEETWATER...SOUTHERN FREMONT AND NATRONA COUNTY
WILL SEE SOME LIGHT SNOW AND RAIN...WITH PERIODS OF LIGHT WET SNOW
IN THE MOUNTAINS. THIS AREA WILL HAVE STRONG NORTHEAST WINDS.
TEMPERATURES WILL BE COLD WITH HIGH RELATIVE HUMIDITY.  MIXING
HEIGHTS WILL BE LOW WITH POOR SMOKE DISPERSAL.

TO THE NORTH AND WEST OF THIS AREA...CLEARING WILL OCCUR WITH THE
WINDS STEADILY DECREASING TOWARDS THE NORTHWEST. WITH SUNSHINE THE
NORTH AND WEST WILL WARM ON FRIDAY. MIXING HEIGHTS WILL INCREASE
WITH AFTERNOON SMOKE DISPERSAL BECOMING GOOD MOST AREAS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER







000
FXUS63 KUNR 162033
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
233 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 228 PM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING.
SCT-BKN040-060 CLOUDS WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER
TONIGHT. EXCEPTION WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON
ACROSS THE HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...HELGESON




000
FXUS63 KUNR 162033
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
233 PM MDT THU APR 16 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW CONTINUES TO SPIN OVER THE FOUR CORNERS AREA...PRODUCING
SOME RAIN ACROSS CO/WY/NE. CWA IS FREE OF PRECIPITATION AT THIS
TIME...UNDER PARTLY TO MOSTLY CLOUDY SKIES. SURFACE HIGH IS
PUSHING IN FROM THE NORTHWEST...AND NORTHWESTERLY WINDS ARE AROUND
20 KTS ACROSS THE AREA. TEMPS ARE RISING INTO THE 50S AND LOWER
60S.

UPPER LOW WILL BEGIN SHIFTING NORTHEASTWARD TONIGHT. KEPT CHANCES OF
PRECIP ACROSS THE SOUTHERN CWA...BUT BEST FRONTOGENESIS STAYS SOUTH
OF THE AREA OVERNIGHT. LOWS WILL BE IN THE 30S AND 40S...WARMEST
ACROSS THE CLOUDIER SOUTH.

THE DEFORMATION ZONE AND JET STREAK WILL APPROACH THE AREA FRIDAY
INTO FRIDAY FRIDAY NIGHT AS LOW TRANSITIONS NORTHEASTWARD. PRECIP
IS LIKELY ACROSS THE SOUTHERN CWA...BUT A SHARP CUTOFF IS EXPECTED
AND SO NORTHWESTERN SD MAY NOT SEE ANYTHING UNTIL SATURDAY. HIGHS
IN THE 50S AND LOWER 60S FRIDAY WILL KEEP MUCH OF THE PRECIP AS
RAIN...BUT LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE ACROSS THE
HILLS FRIDAY NIGHT AS TEMPS COOL NEAR FREEZING. AREAS FARTHER
EAST SHOULD STAY IN THE 40S OVERNIGHT AND REMAIN RAINY. A STRONG
BAND OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE SETS UP OVER THE
SOUTHWESTERN CWA FRIDAY NIGHT...WITH 0.50 TO 0.75 INCH OF RAIN
POSSIBLE THERE OVERNIGHT. HOWEVER...WITH THE CURRENT DROUGHT AND
THE WAY MODELS HAVE HANDLED THE LAST TWO SYSTEMS...WOULD NOT BE
SURPRISED IF MUCH LESS RAIN WAS RECEIVED.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 228 PM MDT THU APR 16 2015

UPPER LOW OVER NORTH CENTRAL CO WILL SPIN NORTHEAST
INTO CENTRAL NE SUNDAY...AND THEN BE WHISKED AWAY BY NORTHERN STREAM
SHORTWAVE DROPPING INTO THE NORTHERN PLAINS. SYSTEM WILL MOVE
QUICKLY INTO THE MIDWEST SUNDAY NIGHT. DEFORMATION ZONE
PRECIPITATION WILL WRAP AROUND THE UPPER LOW WITH POTENTIAL FOR MUCH
NEEDED PRECIPITATION. THIS WILL BE ESPECIALLY TRUE FOR WHEREVER THE
BEST UPPER LEVEL DIVERGENCE LINES UP OVER 850-700MB FRONTOGENESIS.
MODEL GUIDANCE IS WAVERING SOMEWHAT ON HOW MUCH PHASING WILL OCCUR
WITH TWO SYSTEMS. WILL PLAY IT DOWN THE MIDDLE FOR NOW. FORECAST
SOUNDINGS SUGGEST ACCUMULATING SNOW POSSIBLE OVER THE HIGHER
TERRAIN...BUT IT WILL TAKE SUSTAINED MODERATE PRECIPITATION FOR THAT
TO OCCUR. TSRA POSSIBLE SATURDAY AFTERNOON/EVENING.

COOL/SEASONABLE WEATHER EXPECTED NEXT WEEK AS NORTHWEST FLOW
DOMINATES.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 228 PM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING.
SCT-BKN040-060 CLOUDS WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER
TONIGHT. EXCEPTION WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON
ACROSS THE HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...HELGESON
AVIATION...HELGESON



000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF



000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF



000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF



000
FXUS65 KCYS 161805
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1205 PM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1156 AM MDT THU APR 16 2015

IFR/LIFR CIGS AND VSBYS ARE ALREADY OCCURRING WITH WIDESPREAD
MODERATE TO HEAVY SNOW ALONG AND SOUTH OF I80 IN WY. THIS WILL
CONTINUE THROUGH THE DAY WITH SNOW POSSIBLY MIXING WITH RAIN AT
ELEVATIONS BELOW 7000 FEET BY LATE AFTN. KLAR AND KRWL WILL SEE
ALL SNOW THROUGH THE TAF PERIOD...WITH BETTER CHANCES FOR MIXED
PRECIPITATION AT TIMES FOR KCYS. RAIN IS EXPECTED FOR PANHANDLE
TERMINALS. A FEW LIGHTNING STRIKES COULD OCCUR OVER SOUTHEAST WY
AND THE SOUTHERN NE PANHANDLE THIS AFTN AND EVE. RAIN/SNOW RATES
SHOULD DIMINISH OVERNIGHT...BUT ANOTHER ROUND OF HEAVY PRECIP IS
LIKELY ALONG THE I80 CORRIDOR AFTER 09Z FRI. WIDESPREAD IFR
CONDITIONS SHOULD PREVAIL.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL NOON MDT FRIDAY FOR WYZ114>117.

     WINTER WEATHER ADVISORY UNTIL NOON MDT FRIDAY FOR WYZ112-118.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CLH
FIRE WEATHER...ZF



000
FXUS65 KRIW 161759
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1159 AM MDT THU APR 16 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

ALL CONCERNS IN THE SHORT RANGE FOCUS AROUND WHAT WILL HAPPEN WITH
OUR UPPER LEVEL DEVIL...AKA THE UPPER LEVEL LOW THAT BROUGHT THE
HEAVY SNOW TO PORTIONS OF THE AREA. AT THIS TIME...SATELLITE IMAGERY
SHOWS IT DROPPING SOUTHWARD THROUGH UTAH. A SPOKE OF ENERGY IS
BRINGING SOME MAINLY LIGHT SNOW TO PORTIONS OF THE AREA.
HOWEVER...THERE IS SOME DRIER AIR TRYING TO PUNCH INTO EASTERN
PORTIONS OF THE AREA. WITH THAT...WE WILL CANCEL THE WARNING FOR
NATRONA COUNTY AT ISSUANCE. IN THE OTHER AREAS WITH HIGHLIGHTS...WE
WILL LET THEM RIDE UNTIL EXPIRATION MORE THAN LIKELY. MOST OF
TODAY CONDITIONS SHOULD SOMEWHAT IMPROVE AS THE LOW CONTINUES TO
DRIFT SOUTHWARD AND DRIER AIR TRIES TO PUNCH IN FROM THE NORTH.
MOST SHOWERS SHOULD RETREAT TO AROUND THE WIND RIVER RANGE TO
CASPER MOUNTAIN THIS AFTERNOON. SOME SUNSHINE COULD RETURN TO THE
NORTH WITH WARMER TEMPERATURES. HOWEVER...THE REST OF THE AREA
WILL SEE CLOUDS AND A FEW SHOWERS LINGER. ROAD PROBLEMS SHOULD BE
MINIMAL THOUGH...AS THE STRONG APRIL SUN SHOULD MELT ANY SNOW ON
CONTACT. THE NEXT QUESTION IS FOR TONIGHT AS ANOTHER SURGE OF
MOISTURE TRIES TO MOVE NORTHWARD. THE QUESTION IS HOW FAR NORTH
WILL IT GO. AND...LIKE YESTERDAY THERE ARE STILL SOME DIFFERENCES.
THE BEST GUESS AT THIS POINT IS MOST STAYS SOUTH OF A RIVERTON TO
CASPER LINE. CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE
MADE FEW CHANGES. AS FOR HIGHLIGHTS...WITH THE CURRENT ONES STILL
GOING WE WILL LET THE DAY SHIFT MAKE THAT DECISION.
MEANWHILE...DRY WEATHER WILL BE FOUND ACROSS THE NORTHWESTERN HALF
OF THE COUNTY WARNING AREA.

ANOTHER PROBLEM IS FRIDAY AS THE LOW TURNS A BIT TO THE EAST AND
THEN NORTHEAST. AT THE SAME TIME...A BIT OF JET ENERGY WILL ROUND
THE BASE OF IT AND HEAD TOWARD THE SOUTHERN AND EASTERN PORTIONS
OF THE COUNTY WARNING AREA. BOTH THE NAM AND GFS TRY AGAIN TO
BRING A SURGE OF MOISTURE NORTHWARD...THOUGH AGAIN...THE EXACT
NORTHERN EXTENT OF IT IS RATHER UNCERTAIN AT THIS TIME. ONE BIG
DIFFERENCE WITH THIS SURGE IS THAT THERE WILL BE SOME WARMER AIR
WITH THIS SURGE WITH 700 MILLIBAR TEMPERATURES RISING TO AROUND
MINUS 1 TO MINUS 2 CELSIUS. THIS WOULD RAISE SNOW LEVELS TO
BETWEEN 7500 AND 8000 FEET SO MUCH OF THE PRECIPITATION ON THIS
DAY WOULD FALL AS RAIN EXCEPT IN THE MOUNTAINS.

THERE IS MORE UNCERTAINTY FOR SATURDAY AS WELL. A SYSTEM MOVING IN
FROM THE NORTHWEST LOOKS TO FINALLY BE ABLE TO KICK THE UPPER LEVEL
LOW AWAY TO THE NORTH AND EAST. HOWEVER...THE NAM AND GFS SHOW A
BAND OF PRECIPITATION ACROSS THE AREA. AND...OF COURSE...THERE ARE
DIFFERENT LOCATIONS OF WHERE IT WILL SET UP. AT THIS POINT WE MADE
FEW CHANGES. THE SYSTEM MOVING IN FROM THE WEST LOOKS TO BRING SOME
MORE PRECIPITATION TO THE WEST AS WELL BUT AT THIS POINT AMOUNTS ARE
UNCERTAIN.

.LONG TERM...SUNDAY THROUGH THURSDAY NIGHT

THE PATTERN IN THE LONG TERM REMAINS SOMEWHAT CONVOLUTED AS AN
UPSTREAM RIDGE CONTINUES TO BUILD OVER THE NORTHEAST AND EASTERN
CANADA SUNDAY INTO TUESDAY. AS IT DOES SO...AN UPPER LEVEL LOW
MOVING SOUTHWARD FROM THE YUKON TERRITORY...WILL MERGE WITH THE
SYSTEM THAT IS CURRENTLY GENERATING THE RECENT PRECIP OVER THE
CENTRAL ROCKIES. THIS WILL CAUSE THE LOW TO DEEPEN AS IT MAKES ITS
WAY OVER THE UPPER MIDWEST. THIS...IN TURN...WILL GENERATE A
NORTHWEST FLOW PATTERN OVER THE NORTHERN ROCKIES. A COLD FRONT
ASSOCIATED WITH THE CANADIAN SYSTEM WILL MOVE THROUGH THE AREA ON
SUNDAY...WHICH WILL KEEP A SLIGHT CHANCE FOR RAIN AND SNOW SHOWERS
ACROSS MUCH OF THE FORECAST AREA. THIS ACTIVITY WILL BECOME MORE
ISOLATED BY MONDAY AND TUESDAY.

THE LAST PORTIONS OF THE FORECAST PERIOD REMAIN UNCERTAIN...AS A NEW
PACIFIC STORM SYSTEM BEGINS TO MAKES ITS WAY ONSHORE OVER NORTHERN
CALIFORNIA. MODELS ARE TRENDING FOR THIS SYSTEM TO CUT OFF AS IT
DOES SO. AS A RESULT...WEAK SHORTWAVES ROTATING AROUND THIS SYSTEM
COULD MAKE THEIR WAY OVER THE FORECAST AREA FROM THE SOUTHWEST. THE
PROBLEM IS THAT THE COWBOY STATE WILL BE SQUEEZED BETWEEN THIS NEW
LOW AND THE AFOREMENTIONED NORTHWEST FLOW AND WHICH ONE WILL HAVE
THE STRONGER INFLUENCE. AT THIS TIME...LEFT A SLIGHT CHANCE FOR
RAIN/SNOW SHOWERS WEDNESDAY NIGHT...CHANGING TO RAIN DURING THE DAY
THURSDAY.

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF MVFR TO LOCAL IFR CEILINGS AND
VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL CONTINUE ACROSS
NATRONA...SOUTHERN AND EASTERN FREMONT AND SWEETWATER COUNTIES
THROUGH 18Z FRIDAY. NORTH AND WEST OF THIS AREA WILL BE PREVAILING
VFR . LOCAL MVFR CEILINGS AND VISIBILITY REDUCED IN FOG CAN
BE EXPECTED ALONG RIVERS AND LAKES FROM 03Z TO 16Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MVFR/IFR
CEILINGS AND VISIBILITY REDUCED IN LIGHT SNOW AND FOG WILL OCCUR
ACROSS THE SW QUARTER OF WY...VICINITY AND SOUTH OF KBPI...THROUGH
18Z FRIDAY.  GUSTY NE SURFACE WINDS AT 25-35KTS WILL CONTINUE
ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY KRKS.

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS SOME
RAIN AND SNOW SHOWERS AROUND TODAY AND EVEN INTO FRIDAY AS WELL.
THIS MEANS A MAINLY CLOUDY SKY CONTINUED COOL TEMPERATURES. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES ALONG
WITH LOWER HUMIDITY. A GUSTY BREEZE MAY BLOW AT TIMES TODAY...BUT
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...C.BAKER
FIRE WEATHER...HATTINGS







000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON



000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON



000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON



000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON



000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON



000
FXUS63 KUNR 161709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1106 AM MDT THU APR 16 2015

MAINLY VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SCT-
BKN040-060 WILL SLOWLY DISSIPATE WITH SCT-BKN100 LEFTOVER TONIGHT.
EXCEPT WILL BE SOME LINGERING MVFR CIGS THIS AFTERNOON ACROSS THE
HIGHER TERRAIN OF NORTHEAST WY/BLACK HILLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...HELGESON




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 161251
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
651 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 644 AM MDT THU APR 16 2015

WIDESPREAD IFR/LIFR IS EXPECTED AT MOST SITES THROUGH THE MAJORITY
OF THE PERIOD AS LLVL NORTHEAST UPSLOPE FLOW PERSISTS. AFTER A
LULL THIS MORNING PRECIPITATION BECOMES MORE WIDESPREAD BY AROUND
18Z. KLAR WILL CARRY THE GREATEST IMPACT THROUGH THE PERIOD WITH
MODERATE TO LOCALLY HEAVY SNOW FALLING THERE. KRWL WILL SEE LIGHT
SNOW AS WELL...HOWEVER LIGHTER RATES WONT PUSH VISIBILITIES AS LOW
AS KLAR. KCYS IS PROBABLY THE TRICKIEST LOCATION AS THE SNOW
LEVELS HOVER AROUND ITS ELEVATION. FOR NOW EXPECT -SN EARLY TO MIX
WITH RAIN DURING THE OVERNIGHT HOURS. LOCATIONS IN WRN NEBRASKA
WILL SEE ALL -RA DURING THIS EVENT AS WARMER TEMPS PERSIST.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.
&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...ZF



000
FXUS63 KUNR 161139
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
539 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 535 AM MDT THU APR 16 2015

SCT IFR/LIFR CONDITIONS IN LIGHT SNOW WILL GRADUALLY END ACROSS
NERN WY AND THE BLKHLS THIS MORNING. EXP MAINLY VFR CONDS ALL
AREAS BY THIS AFTERNOON...WITH A FEW LINGERING MVFR CIGS POSSIBLE
ACROSS NE WY AND THE BLACK HILLS EARLY THIS AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 161139
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
539 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 535 AM MDT THU APR 16 2015

SCT IFR/LIFR CONDITIONS IN LIGHT SNOW WILL GRADUALLY END ACROSS
NERN WY AND THE BLKHLS THIS MORNING. EXP MAINLY VFR CONDS ALL
AREAS BY THIS AFTERNOON...WITH A FEW LINGERING MVFR CIGS POSSIBLE
ACROSS NE WY AND THE BLACK HILLS EARLY THIS AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...JC




000
FXUS65 KCYS 161035
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
435 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1034 PM MDT WED APR 15 2015

LATEST HRRR GUIDANCE USED FOR THE 06Z TAFS. WIDESPREAD IFR/LIFR
WITH NORTHEAST UPSLOPING FLOW. PRECIP BECOMES WIDESPREAD THURSDAY
AFTERNOON...WITH A POSSIBLE HEAVY SNOW EVENT THURSDAY NIGHT INTO
FRIDAY MORNING FOR SOUTHEAST WYOMING AND A WIDESPREAD MODERATE
RAIN EVENT FOR THE PANHANDLE AIRPORTS.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.

&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...GCC
FIRE WEATHER...ZF



000
FXUS65 KCYS 161035
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
435 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1034 PM MDT WED APR 15 2015

LATEST HRRR GUIDANCE USED FOR THE 06Z TAFS. WIDESPREAD IFR/LIFR
WITH NORTHEAST UPSLOPING FLOW. PRECIP BECOMES WIDESPREAD THURSDAY
AFTERNOON...WITH A POSSIBLE HEAVY SNOW EVENT THURSDAY NIGHT INTO
FRIDAY MORNING FOR SOUTHEAST WYOMING AND A WIDESPREAD MODERATE
RAIN EVENT FOR THE PANHANDLE AIRPORTS.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.

&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...GCC
FIRE WEATHER...ZF



000
FXUS65 KCYS 161035
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
435 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1034 PM MDT WED APR 15 2015

LATEST HRRR GUIDANCE USED FOR THE 06Z TAFS. WIDESPREAD IFR/LIFR
WITH NORTHEAST UPSLOPING FLOW. PRECIP BECOMES WIDESPREAD THURSDAY
AFTERNOON...WITH A POSSIBLE HEAVY SNOW EVENT THURSDAY NIGHT INTO
FRIDAY MORNING FOR SOUTHEAST WYOMING AND A WIDESPREAD MODERATE
RAIN EVENT FOR THE PANHANDLE AIRPORTS.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.

&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...GCC
FIRE WEATHER...ZF



000
FXUS65 KCYS 161035
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
435 AM MDT THU APR 16 2015

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 435 AM MDT THU APR 16 2015

SIGNIFICANT STORM STILL EXPECTED TO IMPACT THE HIGHER ELEVATIONS
FROM LATE THIS AFTERNOON THROUGH MIDDAY FRIDAY. WATER VAPOR
IMAGERY SHOWS THE CLOSED UPPER LOW SPINNING JUST WEST OF THE FOUR
CORNERS REGION. WE ARE GETTING A BREAK IN THE PRECIP...HOWEVER
THIS WILL LIKELY BE SHORT LIVED (ONLY THROUGH THIS MORNING) AS
CLOUD TOPS ARE COOLING IN COLORADO. THE MODELS CONTINUE TO
INDICATE EXCELLENT LARGE SCALE LIFT DEVELOPING IN AREAS ALONG THE
COLORADO BORDER BY LATE THIS AFTN. UPWARD VERTICAL MOTION IS
MAXIMIZED FROM 21Z THIS AFTN THROUGH 12Z FRI IN THE SOUTHERN HALF
OF THE CWA. THIS IS DUE TO EXCELLENT UPPER LEVEL DIFFLUENCE AND
ISENTROPIC LIFT. WHILE WIDESPREAD SUBSTANTIAL QPF AMOUNTS ARE
VERY LIKELY...THE TRICKIER PART OF THIS FCST INVOLVED THE SNOW
LEVEL AND ASSOCIATED SNOW ACCUMULATIONS.

THE 00Z GUIDANCE CAME IN A BIT WARMER THAN YESTERDAY WITH RESPECT
TO SFC TEMPS FROM LATE THIS AFTN THROUGH FRIDAY MORNING. WARM AIR
ADVECTION IS OCCURRING AS 700MB TEMPS AT CHEYENNE RISE FROM -4C
THIS MORNING TO -1C BY FRI MORNING. THE CYS SOUNDING FROM BOTH THE
NAM AND GFS SHOW SFC TEMPS OF 2-3C WITH COMPLETE SATURATION
THROUGH TONIGHT. THUS...DESPITE THE STRONG LLVL LIFT...THINKING
IS THAT A MIX OF RAIN/SNOW OR ALL RAIN WILL OCCUR BETWEEN
ELEVATIONS OF 6250-5500 FT WITH THIS EVENT. DECIDED TO CANCEL THE
WINTER STORM WATCH FOR CENTRAL LARAMIE COUNTY AND EAST PLATTE
COUNTY WITH THIS REASONING...AND WILL LET DAY SHIFT SEE IF THE 12Z
GUIDANCE COMES IN ANY COOLER OR IF ANY DRIER AIR COULD CAUSE SOME
WET-BULBING. THE PRECIP WILL START OUT AS ALL SNOW AT ELEVATIONS
ABOVE 6500 FT THIS AFTN AND EARLY EVENING...WITH THE SNOW LEVEL
POSSIBLY RISING TO AROUND 7500 FT BY FRI MORNING. THE WINTER STORM
WATCH WAS UPGRADED TO A WARNING FROM JUST WEST OF CHEYENNE TO
ARLINGTON AND ALSO FOR THE SNOWY RANGE.  WHILE TRAVEL WILL BE
AFFECTED ALONG INTERSTATE 80 FROM CHEYENNE TO ARLINGTON...THE
BIGGEST IMPACTS WILL LIKELY BE OVER THE FROM BUFORD TO THE
INTERSTATE 80 SUMMIT WHERE UP TO A FOOT OF SNOW IS FCSTED.

BY FRI AFTN THE UPPER LOW WILL HAVE MOVED INTO CENTRAL COLORADO.
THE MODELS SHOW VERY GOOD LIFT AND WIDESPREAD PRECIP ACROSS THE
CWA THROUGH THE AFTN. DECIDED TO END THE WINTER STORM HIGHLIGHTS
AT 18Z FRI AS SFC TEMPS WILL LIKELY BE ABOVE FREEZING ACROSS ALL
ZONES EXPECT MAYBE THE HIGHER ELEVATIONS OF THE SNOWY RANGE. THE
BAND OF PRECIP IS PROGGED TO SHIFT NORTHWARD FROM NORTHERN CARBON
TO THE NORTHERN NEBRASKA PANHANDLE BY FRI EVENING. IT IS AT THIS
TIME THAT DRIER AIR WILL WORK INTO THE SOUTHERN HALF OF THE CWA
AND PRECIP WILL DIMINISH. WITH MOST OF THE MODELS INDICATING QPF
AMOUNTS OF 1.25-2.0 INCHES FROM THIS AFTERNOON THROUGH FRIDAY
NIGHT FOR AREAS ALONG AND EAST OF THE LARAMIE RANGE...CONFIDENCE
IS HIGH THAT THIS SYSTEM WILL BRING WELL NEEDED MOISTURE TO THE
REGION.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 435 AM MDT THU APR 16 2015

A COOL AND SHOWERY PERIOD STILL EXPECTED ACROSS THE CWFA THIS
WEEKEND AND EARLY NEXT WEEK AS NORTHWEST FLOW PREVAILS. REMNANTS
OF THE UPPER LOW THAT WILL HAVE WOBBLED AROUND COLORADO FOR THE
BETTER PART OF 3 DAYS LATE THIS WEEK...WILL CARRY LINGERING
IMPACTS ACROSS THE REGION EVEN INTO SATURDAY. 00Z MEDIUM RANGE
GUIDANCE ARE CONSISTENT IN PINWHEELING A FINAL VORT LOBE SOUTH TO
NORTH THRU THE AREA ON SATURDAY. MODELS TARGET WRN AND NRN ZONES
WITH THE BEST AXIS OF PRECIP ON SATURDAY...THOUGH COOL MID-LEVEL
TEMPS WILL BE ENOUGH TO PRODUCE THE POSSIBILITY OF SHOWERS
EVERYWHERE. FINALLY...THE UPPER-LOW WILL FULLY PHASE INTO THE NRN
STREAM BY SUNDAY. 00Z MODELS HAVE TRENDED DEEPER/STRONGER WITH
KICKER SYSTEM HOWEVER. THIS WILL RE-ENFORCE PRECIP CHANCES FOR
SUNDAY. IT LOOKS SOMEWHAT DRIER MON-TUE...THOUGH STILL CANT
COMPLETELY RULE OUT SOME LIGHT SHOWER ACTIVITY ESPECIALLY IN AND
AROUND THE HIER TERRAIN. ANOTHER WEAK SHORTWAVE MAY BRING ADDL
SHOWER CHANCES TO THE AREA WED-THU. NONE OF THESE SHOWER CHANCES
WILL AMOUNT TO MUCH THO. TEMPS WILL BE THE COOLEST THIS WEEKEND
WITH HIGHS ONLY REACHING THE UPPER 40S TO NR 50 IN AND AROUND THE
MOUNTAINS WITH 50S TO NR 60 OUT ON THE ERN PLAINS. THESE SHOULD
WARM BACK INTO THE 50S AND MID 60S MON-WED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1034 PM MDT WED APR 15 2015

LATEST HRRR GUIDANCE USED FOR THE 06Z TAFS. WIDESPREAD IFR/LIFR
WITH NORTHEAST UPSLOPING FLOW. PRECIP BECOMES WIDESPREAD THURSDAY
AFTERNOON...WITH A POSSIBLE HEAVY SNOW EVENT THURSDAY NIGHT INTO
FRIDAY MORNING FOR SOUTHEAST WYOMING AND A WIDESPREAD MODERATE
RAIN EVENT FOR THE PANHANDLE AIRPORTS.

&&

.FIRE WEATHER...
ISSUED AT 347 AM MDT THU APR 16 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. A COOL AND VERY WET
PATTERN WILL BE IN PLACE THROUGH FRIDAY. WIDESPREAD RAIN ACROSS
THE LOWER ELEVATIONS AND SNOW IN THE MOUNTAINS WILL OCCUR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MDT FRIDAY
     FOR WYZ114>117.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON MDT
     FRIDAY FOR WYZ103-105-106-110-112.

NE...NONE.

&&

$$

SHORT TERM...ZF
LONG TERM...CAH
AVIATION...GCC
FIRE WEATHER...ZF



000
FXUS63 KUNR 160941
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
341 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 334 AM MDT THU APR 16 2015

SCT IFR/LIFR CONDITIONS IN RAIN/SNOW WILL CONTINUE INTO ACROSS
NERN WY AND THE BLKHLS THIS MORNING. MVFR CIGS IN RAIN EXPECTED
OVER THE WRN SD PLAINS. SLOW IMPROVEMENT EXPECTED THURSDAY
AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...JC



000
FXUS63 KUNR 160941
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
341 AM MDT THU APR 16 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 334 AM MDT THU APR 16 2015

WATER VAPOR IMAGERY SHOWS LARGE CUT OFF CENTERED ALONG THE UT/CO
BORDER...WITH SEVERAL WAVES MOVING NORTHWARD ACROSS THE CNTRL TO NRN
HIGH PLAINS. SURFACE ANALYSIS SHOWS A NEARLY STATIONARY FRONT
STRADDLED ACROSS THE WRN SD PLAINS...WITH TEMPS IN THE 30S OVER NE
WY TO UPPER 40S/LOW 50S OVER CNTRL SD. KUDX RADAR SHOWS RAIN FALLING
ACROSS PORTIONS OF NW SD...AND A BAND MOVING INTO SW SD. IR SAT/OBS
SHOW MORE PRECIP FALLING OVER NE...WITH GCC REPORTING SNOW WHILE
HULETT AND NEWCASTLE ARE REPORTING RAIN. NE WY SPOTTERS HAVE
REPORTED SNOW FALLING WITH LITTLE TO NO ACCUMULATION AS MOST OF IT
MELTED UPON REACHING THE GROUND. THE MULE CREEK JUNCTION AND HIGHWAY
59 REST STOP WEB CAMS BOTH SHOW ACCUMULATIONS OF AROUND AN INCH.
TEMPERATURES ARE RIGHT AT FREEZING OR JUST ABOVE...SO LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. WILL CANCEL THE WINTER WEATHER
ADVISORY WITH THE MORNING PACKAGE. UPPER LOW WILL DRIFT E/SE
TODAY...BUT MAKE VERY LITTLE MOVEMENT OVERALL AS WEAK RIDGING
DEVELOPS OVER THE CNDN ROCKIES SETTING UP A REX BLOCK TONIGHT.
PRECIP WILL GRADUALLY DECREASE TODAY...BUT STILL LINGER IN SOME
AREAS. TEMPS WILL REACH THE MID TO UPPER 40S OVER NE WY TO THE 60S
ACROSS CNTRL SD.

DEFORMATION ZONE WILL CO/KS/NEB TODAY AND TONIGHT...BUT MODELS ARE
SHOWING A NORTHWARD PUSH WITH THE LOW AS THE NEXT SHORTWAVE TROUGH
CROSSES THE CNDN HIGH PLAINS...BEGINNING A PHASE IN PROCESS IN THE
LONG TERM. THE RESULT IS THE DEFORMATION ZONE SLOWLY MOVING
NORTHWARD INTO THE CWA. HAVE RAISED POPS QUITE A BIT ACROSS THE AREA
TO ACCOUNT FOR THIS. QPF AMOUNTS ARE VARYING...BUT IT WILL BE
POSSIBLE THE MANY LOCATIONS WILL HAVE AN INCH OR MORE OF LIQUID
ACROSS SW SD BY LATE FRI NIGHT...WITH MORE IN THE EARLY LONG TERM.
LOW LEVELS WILL BE WARM ENOUGH TO KEEP THIS AS RAIN...BUT HIGHER
ELEVATIONS OF THE BLACK HILLS MAY SEE LIGHT ACCUMULATIONS OF SNOW
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 334 AM MDT THU APR 16 2015

ACTIVE NORTHWEST FLOW WILL CONTINUE IN THE PERIOD. FORECAST
MODELS CONTINUE TO TREND TO PHASING OF THE CLOSED CENTRAL CONUS
LOW WITH A STRONGER NORTHERN STREAM TROUGH SAT...SUPPORTING PRECIP
CHANCES ACROSS THE REGION. DEEP SOUTHERLY FLOW AHEAD OF THE CLOSED
CENTRAL CONUS UPPER LOW WILL SUPPORT AMPLE MOISTURE WITH THIS
SYSTEM...ALLOWING A DECENT CHANCE FOR PRECIP ACROSS MUCH OF THE
FA. IN FACT...THE GFS AND ECMWF BOTH SUPPORT OVER AN INCH OF QPF
OVER WESTER SD...WITH THE GFS PROGGING OVER 2 INCHES IN SOME
AREAS. GIVEN GROWING SUPPORT ACROSS MODEL AND ENSEMBLE
SPECTRUMS...HAVE INCREASED POPS SAT. SOME SNOW LOOKS POSSIBLE
ACROSS THE HIGHER TERRAIN. HOWEVER...ATTM GIVEN WARM THERMAL
FIELDS...PRECIP LOOKS TO FALL AS RAIN OVER MUCH OF THE FA. THIS
WILL NEED TO BE MONITORED FOR THE HIGHER TERRAIN OF THE BLACK
HILLS...AS A SLIGHT SHIFT IN THERMAL FIELDS COULD SUPPORT DECENT
SNOWS. CAA AND DRY NW TRAJECTORIES WILL BRING DRY WEATHER TO MOST
OF THE AREA THROUGH THE REMAINDER OF THE PERIOD...SAVE TOWARD THE
END OF NEXT WEEK WHEN AN EASTERN NOAM CLOSED LOW MAY RETROGRADE
BACK WEST INTO THE REGION PER LONGWAVE FLOW RETROGRESSION OVER
WESTERN NOAM. MUCH UNCERTAINTY PER THE EVOLUTION OF THE LARGE
SCALE FLOW TOWARD THE END OF THE PERIOD GIVEN CONCERNS ON CLOSED
UPPER LOWS AND WILDLY DIFFERENT SOLUTIONS PER EASTERN PAC FLOW
EVOLUTION. THUS...KEPT POPS LOW AND CLOSE TO PREVIOUS FORECAST
NUMBERS UNTIL STRONGER SIGNALS MATERIALIZE. OVERALL...COOL CONDS
CAN BE EXPECTED FOR MOST OF THE LONG TERM PERIOD GIVEN A STRONG
INFLUENCE OF THE EXPECTED EASTERN NOAM UPPER LEVEL TROUGH AND
ASSOCIATED BLOCKED FLOW.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 334 AM MDT THU APR 16 2015

SCT IFR/LIFR CONDITIONS IN RAIN/SNOW WILL CONTINUE INTO ACROSS
NERN WY AND THE BLKHLS THIS MORNING. MVFR CIGS IN RAIN EXPECTED
OVER THE WRN SD PLAINS. SLOW IMPROVEMENT EXPECTED THURSDAY
AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...13
LONG TERM...JC
AVIATION...JC




000
FXUS65 KRIW 160903
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
303 AM MDT THU APR 16 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

ALL CONCERNS IN THE SHORT RANGE FOCUS AROUND WHAT WILL HAPPEN WITH
OUR UPPER LEVEL DEVIL...AKA THE UPPER LEVEL LOW THAT BROUGHT THE
HEAVY SNOW TO PORTIONS OF THE AREA. AT THIS TIME...SATELLITE IMAGERY
SHOWS IT DROPPING SOUTHWARD THROUGH UTAH. A SPOKE OF ENERGY IS
BRINGING SOME MAINLY LIGHT SNOW TO PORTIONS OF THE AREA.
HOWEVER...THERE IS SOME DRIER AIR TRYING TO PUNCH INTO EASTERN
PORTIONS OF THE AREA. WITH THAT...WE WILL CANCEL THE WARNING FOR
NATRONA COUNTY AT ISSUANCE. IN THE OTHER AREAS WITH HIGHLIGHTS...WE
WILL LET THEM RIDE UNTIL EXPIRATION MORE THAN LIKELY. MOST OF
TODAY CONDITIONS SHOULD SOMEWHAT IMPROVE AS THE LOW CONTINUES TO
DRIFT SOUTHWARD AND DRIER AIR TRIES TO PUNCH IN FROM THE NORTH.
MOST SHOWERS SHOULD RETREAT TO AROUND THE WIND RIVER RANGE TO
CASPER MOUNTAIN THIS AFTERNOON. SOME SUNSHINE COULD RETURN TO THE
NORTH WITH WARMER TEMPERATURES. HOWEVER...THE REST OF THE AREA
WILL SEE CLOUDS AND A FEW SHOWERS LINGER. ROAD PROBLEMS SHOULD BE
MINIMAL THOUGH...AS THE STRONG APRIL SUN SHOULD MELT ANY SNOW ON
CONTACT. THE NEXT QUESTION IS FOR TONIGHT AS ANOTHER SURGE OF
MOISTURE TRIES TO MOVE NORTHWARD. THE QUESTION IS HOW FAR NORTH
WILL IT GO. AND...LIKE YESTERDAY THERE ARE STILL SOME DIFFERENCES.
THE BEST GUESS AT THIS POINT IS MOST STAYS SOUTH OF A RIVERTON TO
CASPER LINE. CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE
MADE FEW CHANGES. AS FOR HIGHLIGHTS...WITH THE CURRENT ONES STILL
GOING WE WILL LET THE DAY SHIFT MAKE THAT DECISION.
MEANWHILE...DRY WEATHER WILL BE FOUND ACROSS THE NORTHWESTERN HALF
OF THE COUNTY WARNING AREA.

ANOTHER PROBLEM IS FRIDAY AS THE LOW TURNS A BIT TO THE EAST AND
THEN NORTHEAST. AT THE SAME TIME...A BIT OF JET ENERGY WILL ROUND
THE BASE OF IT AND HEAD TOWARD THE SOUTHERN AND EASTERN PORTIONS
OF THE COUNTY WARNING AREA. BOTH THE NAM AND GFS TRY AGAIN TO
BRING A SURGE OF MOISTURE NORTHWARD...THOUGH AGAIN...THE EXACT
NORTHERN EXTENT OF IT IS RATHER UNCERTAIN AT THIS TIME. ONE BIG
DIFFERENCE WITH THIS SURGE IS THAT THERE WILL BE SOME WARMER AIR
WITH THIS SURGE WITH 700 MILLIBAR TEMPERATURES RISING TO AROUND
MINUS 1 TO MINUS 2 CELSIUS. THIS WOULD RAISE SNOW LEVELS TO
BETWEEN 7500 AND 8000 FEET SO MUCH OF THE PRECIPITATION ON THIS
DAY WOULD FALL AS RAIN EXCEPT IN THE MOUNTAINS.

THERE IS MORE UNCERTAINTY FOR SATURDAY AS WELL. A SYSTEM MOVING IN
FROM THE NORTHWEST LOOKS TO FINALLY BE ABLE TO KICK THE UPPER LEVEL
LOW AWAY TO THE NORTH AND EAST. HOWEVER...THE NAM AND GFS SHOW A
BAND OF PRECIPITATION ACROSS THE AREA. AND...OF COURSE...THERE ARE
DIFFERENT LOCATIONS OF WHERE IT WILL SET UP. AT THIS POINT WE MADE
FEW CHANGES. THE SYSTEM MOVING IN FROM THE WEST LOOKS TO BRING SOME
MORE PRECIPITATION TO THE WEST AS WELL BUT AT THIS POINT AMOUNTS ARE
UNCERTAIN.

.LONG TERM...SUNDAY THROUGH THURSDAY NIGHT

THE PATTERN IN THE LONG TERM REMAINS SOMEWHAT CONVOLUTED AS AN
UPSTREAM RIDGE CONTINUES TO BUILD OVER THE NORTHEAST AND EASTERN
CANADA SUNDAY INTO TUESDAY. AS IT DOES SO...AN UPPER LEVEL LOW
MOVING SOUTHWARD FROM THE YUKON TERRITORY...WILL MERGE WITH THE
SYSTEM THAT IS CURRENTLY GENERATING THE RECENT PRECIP OVER THE
CENTRAL ROCKIES. THIS WILL CAUSE THE LOW TO DEEPEN AS IT MAKES ITS
WAY OVER THE UPPER MIDWEST. THIS...IN TURN...WILL GENERATE A
NORTHWEST FLOW PATTERN OVER THE NORTHERN ROCKIES. A COLD FRONT
ASSOCIATED WITH THE CANADIAN SYSTEM WILL MOVE THROUGH THE AREA ON
SUNDAY...WHICH WILL KEEP A SLIGHT CHANCE FOR RAIN AND SNOW SHOWERS
ACROSS MUCH OF THE FORECAST AREA. THIS ACTIVITY WILL BECOME MORE
ISOLATED BY MONDAY AND TUESDAY.

THE LAST PORTIONS OF THE FORECAST PERIOD REMAIN UNCERTAIN...AS A NEW
PACIFIC STORM SYSTEM BEGINS TO MAKES ITS WAY ONSHORE OVER NORTHERN
CALIFORNIA. MODELS ARE TRENDING FOR THIS SYSTEM TO CUT OFF AS IT
DOES SO. AS A RESULT...WEAK SHORTWAVES ROTATING AROUND THIS SYSTEM
COULD MAKE THEIR WAY OVER THE FORECAST AREA FROM THE SOUTHWEST. THE
PROBLEM IS THAT THE COWBOY STATE WILL BE SQUEEZED BETWEEN THIS NEW
LOW AND THE AFOREMENTIONED NORTHWEST FLOW AND WHICH ONE WILL HAVE
THE STRONGER INFLUENCE. AT THIS TIME...LEFT A SLIGHT CHANCE FOR
RAIN/SNOW SHOWERS WEDNESDAY NIGHT...CHANGING TO RAIN DURING THE DAY
THURSDAY.

&&

.AVIATION.../12Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VICINITY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VICINITY KCOD-KLND...UNTIL AROUND 12Z. A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BETWEEN 12Z AND 16Z RESULTING
IN CEILINGS GRADUALLY LIFTING AND MOST -SN ENDING. ANOTHER BATCH OF
RAIN AND SNOW SHOWERS MAY ROTATE WESTWARD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS
ACTIVITY EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z
FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MFVR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VICINITY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SURFACE WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY KRKS.
&&

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS SOME
RAIN AND SNOW SHOWERS AROUND TODAY AND EVEN INTO FRIDAY AS WELL.
THIS MEANS A MAINLY CLOUDY SKY CONTINUED COOL TEMPERATURES. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES ALONG
WITH LOWER HUMIDITY. A GUSTY BREEZE MAY BLOW AT TIMES TODAY...BUT
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY.
&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT EARLY THIS MORNING
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT EARLY THIS MORNING
WYZ014-015-018-019.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...AEM
FIRE WEATHER...HATTINGS









000
FXUS65 KRIW 160903
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
303 AM MDT THU APR 16 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

ALL CONCERNS IN THE SHORT RANGE FOCUS AROUND WHAT WILL HAPPEN WITH
OUR UPPER LEVEL DEVIL...AKA THE UPPER LEVEL LOW THAT BROUGHT THE
HEAVY SNOW TO PORTIONS OF THE AREA. AT THIS TIME...SATELLITE IMAGERY
SHOWS IT DROPPING SOUTHWARD THROUGH UTAH. A SPOKE OF ENERGY IS
BRINGING SOME MAINLY LIGHT SNOW TO PORTIONS OF THE AREA.
HOWEVER...THERE IS SOME DRIER AIR TRYING TO PUNCH INTO EASTERN
PORTIONS OF THE AREA. WITH THAT...WE WILL CANCEL THE WARNING FOR
NATRONA COUNTY AT ISSUANCE. IN THE OTHER AREAS WITH HIGHLIGHTS...WE
WILL LET THEM RIDE UNTIL EXPIRATION MORE THAN LIKELY. MOST OF
TODAY CONDITIONS SHOULD SOMEWHAT IMPROVE AS THE LOW CONTINUES TO
DRIFT SOUTHWARD AND DRIER AIR TRIES TO PUNCH IN FROM THE NORTH.
MOST SHOWERS SHOULD RETREAT TO AROUND THE WIND RIVER RANGE TO
CASPER MOUNTAIN THIS AFTERNOON. SOME SUNSHINE COULD RETURN TO THE
NORTH WITH WARMER TEMPERATURES. HOWEVER...THE REST OF THE AREA
WILL SEE CLOUDS AND A FEW SHOWERS LINGER. ROAD PROBLEMS SHOULD BE
MINIMAL THOUGH...AS THE STRONG APRIL SUN SHOULD MELT ANY SNOW ON
CONTACT. THE NEXT QUESTION IS FOR TONIGHT AS ANOTHER SURGE OF
MOISTURE TRIES TO MOVE NORTHWARD. THE QUESTION IS HOW FAR NORTH
WILL IT GO. AND...LIKE YESTERDAY THERE ARE STILL SOME DIFFERENCES.
THE BEST GUESS AT THIS POINT IS MOST STAYS SOUTH OF A RIVERTON TO
CASPER LINE. CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE
MADE FEW CHANGES. AS FOR HIGHLIGHTS...WITH THE CURRENT ONES STILL
GOING WE WILL LET THE DAY SHIFT MAKE THAT DECISION.
MEANWHILE...DRY WEATHER WILL BE FOUND ACROSS THE NORTHWESTERN HALF
OF THE COUNTY WARNING AREA.

ANOTHER PROBLEM IS FRIDAY AS THE LOW TURNS A BIT TO THE EAST AND
THEN NORTHEAST. AT THE SAME TIME...A BIT OF JET ENERGY WILL ROUND
THE BASE OF IT AND HEAD TOWARD THE SOUTHERN AND EASTERN PORTIONS
OF THE COUNTY WARNING AREA. BOTH THE NAM AND GFS TRY AGAIN TO
BRING A SURGE OF MOISTURE NORTHWARD...THOUGH AGAIN...THE EXACT
NORTHERN EXTENT OF IT IS RATHER UNCERTAIN AT THIS TIME. ONE BIG
DIFFERENCE WITH THIS SURGE IS THAT THERE WILL BE SOME WARMER AIR
WITH THIS SURGE WITH 700 MILLIBAR TEMPERATURES RISING TO AROUND
MINUS 1 TO MINUS 2 CELSIUS. THIS WOULD RAISE SNOW LEVELS TO
BETWEEN 7500 AND 8000 FEET SO MUCH OF THE PRECIPITATION ON THIS
DAY WOULD FALL AS RAIN EXCEPT IN THE MOUNTAINS.

THERE IS MORE UNCERTAINTY FOR SATURDAY AS WELL. A SYSTEM MOVING IN
FROM THE NORTHWEST LOOKS TO FINALLY BE ABLE TO KICK THE UPPER LEVEL
LOW AWAY TO THE NORTH AND EAST. HOWEVER...THE NAM AND GFS SHOW A
BAND OF PRECIPITATION ACROSS THE AREA. AND...OF COURSE...THERE ARE
DIFFERENT LOCATIONS OF WHERE IT WILL SET UP. AT THIS POINT WE MADE
FEW CHANGES. THE SYSTEM MOVING IN FROM THE WEST LOOKS TO BRING SOME
MORE PRECIPITATION TO THE WEST AS WELL BUT AT THIS POINT AMOUNTS ARE
UNCERTAIN.

.LONG TERM...SUNDAY THROUGH THURSDAY NIGHT

THE PATTERN IN THE LONG TERM REMAINS SOMEWHAT CONVOLUTED AS AN
UPSTREAM RIDGE CONTINUES TO BUILD OVER THE NORTHEAST AND EASTERN
CANADA SUNDAY INTO TUESDAY. AS IT DOES SO...AN UPPER LEVEL LOW
MOVING SOUTHWARD FROM THE YUKON TERRITORY...WILL MERGE WITH THE
SYSTEM THAT IS CURRENTLY GENERATING THE RECENT PRECIP OVER THE
CENTRAL ROCKIES. THIS WILL CAUSE THE LOW TO DEEPEN AS IT MAKES ITS
WAY OVER THE UPPER MIDWEST. THIS...IN TURN...WILL GENERATE A
NORTHWEST FLOW PATTERN OVER THE NORTHERN ROCKIES. A COLD FRONT
ASSOCIATED WITH THE CANADIAN SYSTEM WILL MOVE THROUGH THE AREA ON
SUNDAY...WHICH WILL KEEP A SLIGHT CHANCE FOR RAIN AND SNOW SHOWERS
ACROSS MUCH OF THE FORECAST AREA. THIS ACTIVITY WILL BECOME MORE
ISOLATED BY MONDAY AND TUESDAY.

THE LAST PORTIONS OF THE FORECAST PERIOD REMAIN UNCERTAIN...AS A NEW
PACIFIC STORM SYSTEM BEGINS TO MAKES ITS WAY ONSHORE OVER NORTHERN
CALIFORNIA. MODELS ARE TRENDING FOR THIS SYSTEM TO CUT OFF AS IT
DOES SO. AS A RESULT...WEAK SHORTWAVES ROTATING AROUND THIS SYSTEM
COULD MAKE THEIR WAY OVER THE FORECAST AREA FROM THE SOUTHWEST. THE
PROBLEM IS THAT THE COWBOY STATE WILL BE SQUEEZED BETWEEN THIS NEW
LOW AND THE AFOREMENTIONED NORTHWEST FLOW AND WHICH ONE WILL HAVE
THE STRONGER INFLUENCE. AT THIS TIME...LEFT A SLIGHT CHANCE FOR
RAIN/SNOW SHOWERS WEDNESDAY NIGHT...CHANGING TO RAIN DURING THE DAY
THURSDAY.

&&

.AVIATION.../12Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VICINITY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VICINITY KCOD-KLND...UNTIL AROUND 12Z. A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BETWEEN 12Z AND 16Z RESULTING
IN CEILINGS GRADUALLY LIFTING AND MOST -SN ENDING. ANOTHER BATCH OF
RAIN AND SNOW SHOWERS MAY ROTATE WESTWARD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS
ACTIVITY EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z
FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VICINITY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCCASIONAL MFVR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VICINITY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SURFACE WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VICINITY KRKS.
&&

.FIRE WEATHER...

UNSETTLED WEATHER WILL CONTINUE MAINLY SOUTH OF A RIVERTON TO NORTH
OF CASPER LINE AS AN UPPER LEVEL LOW KEEPS CLOUDS AS WELL AS SOME
RAIN AND SNOW SHOWERS AROUND TODAY AND EVEN INTO FRIDAY AS WELL.
THIS MEANS A MAINLY CLOUDY SKY CONTINUED COOL TEMPERATURES. FURTHER
NORTH AND WEST...EXPECT MORE SUNSHINE AND WARMER TEMPERATURES ALONG
WITH LOWER HUMIDITY. A GUSTY BREEZE MAY BLOW AT TIMES TODAY...BUT
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY.
&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT EARLY THIS MORNING
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT EARLY THIS MORNING
WYZ014-015-018-019.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...AEM
FIRE WEATHER...HATTINGS










000
FXUS65 KRIW 160601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1201 AM MDT THU APR 16 2015

.UPDATE...CANCELLED WINTER WX ADVISORY FOR EASTERN JOHNSON COUNTY
AND WINTER STORM WARNING FOR OWL CREEK AND BRIDGER MTNS...WHERE
SNOW HAD ENDED OR BECOME INTERMITTENT AND LIGHT.

&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VCNTY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VCNTY KCOD-KLND...THROUGH 12Z.  A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BTWN 12Z AND 16Z RESULTING IN
CIGS GRADUALLY LIFTING AND MOST -SN ENDING.  ANOTHER BATCH OF RAIN
AND SNOW SHOWERS MAY ROTATE WWD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS ACTIVITY
EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VCNTY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCNL MVFR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VCNTY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SFC WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VCNTY KRKS.


&&

.PREV DISCUSSION... /ISSUED 921 PM MDT WED APR 15 2015/

UPDATE...
CANCELLED WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR
PORTIONS OF CENTRAL WYOMING WHERE SNOW HAS ENDED OR BECOME VERY
LIGHT.

PREV DISCUSSION... /ISSUED 631 PM MDT WED APR 15 2015/

UPDATE...ALLOWED WINTER WEATHER ADVISORY TO EXPIRE FOR ZONE 12.
ALL OTHER WINTER STORM WARNINGS/ADVISORIES REMAIN IN EFFECT.
BAROCLINIC LEAF AND HEAVIER PRECIPITATION THAT STRETCHED FROM SE
WY INTO NORTH CENTRAL WY THIS AFTERNOON HAS DISSIPATED AS LARGER
STORMS FORMED OVER THE NEBRASKA PANHANDLE. MAINLY UPSLOPE FAVORED
AREAS...CASPER...LANDER AND ADJACENT MOUNTAINS...RECEIVING THE
HEAVIER SNOWFALL EARLY THIS EVENING.

PREV DISCUSSION... /ISSUED 238 PM MDT WED APR 15 2015/

SHORT TERM...TONIGHT THROUGH THURSDAY

UPPER LEVEL LOW CUT OFF IN FAVORABLE LOCATION BETWEEN VERNAL
UTAH AND GRAND JUNCTION COLORADO WITH TROUGH OF WARM AIR ALOFT
AND OCCLUSION OVER NATRONA AND FREMONT COUNTIES. THIS IS ALSO
ASSOCIATED WITH A JET STREAK PRODUCING STRONG UPPER DIVERGENCE.
STRONG FRONTOGENESIS OCCURRING WITH MID LEVEL DEFORMATION.
SATELLITE PRECIPITABLE WATER ESTIMATES OVER 200 PERCENT OF NORMAL
ALSO ASSOCIATED WITH THESE FEATURES. THIS IS RESULTING IN A SWATH
OF MODERATE TO HEAVY SNOW...ALSO BEING AIDED BY STRONG OROGRAPHIC
LIFT OVER THE WIND RIVER MOUNTAINS AND CASPER MOUNTAIN AS WELL AS
THE GREEN AND RATTLESNAKE RANGES AND THE OWL CREEK AND BRIDGER
MOUNTAINS. MODELS IN FAIR AGREEMENT WITH CONTINUED SNOWFALL
THROUGH THE NIGHT TAPERING OFF IN THE MORNING AS THE UPPER CUT OFF
LOW SINKS SOUTH INTO SOUTHWEST COLORADO. WINTER STORM WARNINGS IN
EFFECT FOR NATRONA...FREMONT AND HOT SPRINGS COUNTIES. AREAS NORTH
AND SOUTH OF THE HEAVY SNOW BAND ARE IN WINTER WEATHER ADVISORIES
TONIGHT. THE WESTERN LOCATIONS...THE GREEN RIVER BASIN...ABSAROKA
MOUNTAINS AND CODY FOOTHILL EXPECTED TO SEE SNOW TAPER OFF AROUND
MIDNIGHT AND ADVISORIES WILL END IN THESE LOCATIONS THEN. SNOWFALL
AROUND 15 INCHES IN THE WINDS AND CASPER MOUNTAINS SHOULD BE
WIDESPREAD WITH LOCAL 20 INCH AMOUNTS POSSIBLE. LANDER...CASPER
AND THERMOPOLIS SHOULD SEE AROUND 10 INCHES ON THE SOUTH SIDE OF
THESE TOWNS ADJACENT TO THE MOUNTAINS WITH DECREASING AMOUNTS AWAY
FROM THE MOUNTAINS. TEMPERATURES WILL BE COLD TONIGHT THROUGH
THURSDAY. PARTIAL CLEARING WILL OCCUR FROM NORTHWEST TO SOUTHEAST
THROUGH THURSDAY.

LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

BY THURSDAY NIGHT THE TWO JET STREAMS SPLIT...DEPOSITING OUR CURRENT
CUTOFF LOW IN BETWEEN THE TWO TRACKS AND LEAVING IT TO SIT AND SPIN
THERE FOR A FEW DAYS. AS THE UPPER LOW SPINS OVER COLORADO...IT WILL
KICK UP SOME MOISTURE AROUND THE LOW WHICH WILL CONTINUE THE
POTENTIAL FOR RAIN AND SNOW ACROSS EASTERN PORTIONS OF THE FORECAST
AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THIS BAND OF
PRECIPITATION WILL SET UP BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO AS FAR WEST AS FREMONT AND SWEETWATER COUNTIES. WE WILL
BE ON A SLOW WARMING TREND HOWEVER...SO MOST OF THIS PRECIPITATION
IS EXPECTED TO FALL AS RAIN.

THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE NORTHERN STORM
TRACK ALONG OUR BORDER WITH CANADA...THIS WILL EVENTUALLY SWING DOWN
ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED LOW TO FINALLY MOVE ON
INTO THE PLAINS. THIS KICKER SYSTEM COULD ENCOURAGE SOME SHOWERS AS
IT SWINGS ON THROUGH...WITH SOME SHOWERS CONTINUING INTO SUNDAY AS
THE COLD POOL ALOFT MOVES OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE
FOR ANOTHER DAY.

YET ANOTHER SHORT WAVE COULD MOVE AROUND THE BASE OF THE TROUGH ON
MONDAY...MOST OF THE ENERGY WITH THIS SYSTEM AT THIS TIME APPEARS TO
REMAIN TO OUR SOUTH BUT IT COULD AT LEAST DRAW DOWN ANOTHER COLD
FRONT ACROSS THE AREA. THERE IS SOME DISAGREEMENT IN THE MODEL
SOLUTIONS AFTER MONDAY ABOUT WHAT HAPPENS NEXT...ONE BUILDS A VERY
WEAK BUT SLIGHTLY WARMER RIDGE INTO THE REGION WHILE THE OTHER KEEPS
THE REGION WET AND UNSETTLED THROUGH MID WEEK. EITHER WAY...IT LOOKS
LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE RECORDS NEXT WEEK
AND WE COULD HAVE A FEW MORE CHANCES FOR SOME PRECIPITATION...WHICH
IS NOT TOO SURPRISING GIVEN THIS IS USUALLY THE WETTEST TIME OF THE
YEAR.

AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

SNOW WILL CONTINUE ACROSS CENTRAL WYOMING...ESPECIALLY ACROSS THE
KLND...KRIW...AND KCPR SITES...THIS EVENING AND LIKELY THROUGH THE
NIGHT. IFR CONDITIONS WILL BE LIKELY ACROSS AREAS WITH SNOW.
NORTHERN PORTIONS OF WYOMING WILL STILL SEE SCATTERED SNOW SHOWERS
AND TIMES OF IFR/MVFR CONDITIONS TONIGHT...WITH IMPROVING CONDITIONS
EXPECTED ACROSS THE NORTH LATE TONIGHT INTO THURSDAY MORNING. GUSTY
WINDS...PEAKING AROUND 30 TO 40 KNOTS...WILL ALSO BE POSSIBLE ACROSS MANY
TERMINALS THIS EVENING INTO THURSDAY MORNING. MOST AREAS WILL THEN
HAVE IMPROVING CONDITIONS THURSDAY AFTERNOON...WITH VFR CONDITIONS
LIKELY RETURNING TO ALL SITES. MOUNTAINS WILL ALSO REMAIN OBSCURED
THROUGH THE NIGHT.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

EXPECT SCATTERED AREAS OF SNOW TO OCCUR THIS EVENING...ESPECIALLY
ACROSS THE KBPI...KPNA...AND KRKS TERMINALS. MVFR/IFR CONDITIONS
WILL LIKELY OCCUR ACROSS AREAS WITH SNOW. MOUNTAINS WILL BE
FREQUENTLY BE OBSCURED THROUGH THIS EVENING. GUSTY WINDS WILL ALSO
BE FOUND ACROSS SOUTHERN PORTIONS...MAINLY NEAR THE KRKS TERMINAL.
ISOLATED VFR CONDITIONS WILL BEGIN TO OCCUR AT SOME OF THE TERMINAL
SITES LATER THIS EVENING...WITH WIDESPREAD VFR CONDITIONS RETURNING
THURSDAY MORNING. PLEASE SEE INDIVIDUAL TERMINAL SITES FOR MORE
DETAILS.

FIRE WEATHER...

SNOWFALL WILL BE RATHER WIDESPREAD TONIGHT COMING TO AN END ON
THURSDAY. SIGNIFICANT SNOWFALLS ARE EXPECTED IN FREMONT...HOT SPRINGS
AND NATRONA COUNTIES. LOWER SNOWFALL AMOUNTS ARE EXPECTED TO THE
NORTH AND SOUTH OF THESE COUNTIES. HIGH RELATIVE HUMIDITY AND COLD
TEMPERATURES WITH LOW MIXING HEIGHTS AND POOR SMOKE DISPERSAL WILL
ALSO OCCUR THROUGH THURSDAY. STRONG NORTHEAST WINDS WILL PRODUCE
AREAS OF BLOWING AND DRIFTING SNOW WITH NEAR ZERO VISIBILITY AT
TIMES TONIGHT AND EARLY THURSDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT THURSDAY
WYZ014-015-018>020-022.

&&

$$

UPDATE...AEM
SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER






000
FXUS65 KRIW 160601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1201 AM MDT THU APR 16 2015

.UPDATE...CANCELLED WINTER WX ADVISORY FOR EASTERN JOHNSON COUNTY
AND WINTER STORM WARNING FOR OWL CREEK AND BRIDGER MTNS...WHERE
SNOW HAD ENDED OR BECOME INTERMITTENT AND LIGHT.

&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VCNTY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VCNTY KCOD-KLND...THROUGH 12Z.  A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BTWN 12Z AND 16Z RESULTING IN
CIGS GRADUALLY LIFTING AND MOST -SN ENDING.  ANOTHER BATCH OF RAIN
AND SNOW SHOWERS MAY ROTATE WWD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS ACTIVITY
EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VCNTY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCNL MVFR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VCNTY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SFC WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VCNTY KRKS.


&&

.PREV DISCUSSION... /ISSUED 921 PM MDT WED APR 15 2015/

UPDATE...
CANCELLED WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR
PORTIONS OF CENTRAL WYOMING WHERE SNOW HAS ENDED OR BECOME VERY
LIGHT.

PREV DISCUSSION... /ISSUED 631 PM MDT WED APR 15 2015/

UPDATE...ALLOWED WINTER WEATHER ADVISORY TO EXPIRE FOR ZONE 12.
ALL OTHER WINTER STORM WARNINGS/ADVISORIES REMAIN IN EFFECT.
BAROCLINIC LEAF AND HEAVIER PRECIPITATION THAT STRETCHED FROM SE
WY INTO NORTH CENTRAL WY THIS AFTERNOON HAS DISSIPATED AS LARGER
STORMS FORMED OVER THE NEBRASKA PANHANDLE. MAINLY UPSLOPE FAVORED
AREAS...CASPER...LANDER AND ADJACENT MOUNTAINS...RECEIVING THE
HEAVIER SNOWFALL EARLY THIS EVENING.

PREV DISCUSSION... /ISSUED 238 PM MDT WED APR 15 2015/

SHORT TERM...TONIGHT THROUGH THURSDAY

UPPER LEVEL LOW CUT OFF IN FAVORABLE LOCATION BETWEEN VERNAL
UTAH AND GRAND JUNCTION COLORADO WITH TROUGH OF WARM AIR ALOFT
AND OCCLUSION OVER NATRONA AND FREMONT COUNTIES. THIS IS ALSO
ASSOCIATED WITH A JET STREAK PRODUCING STRONG UPPER DIVERGENCE.
STRONG FRONTOGENESIS OCCURRING WITH MID LEVEL DEFORMATION.
SATELLITE PRECIPITABLE WATER ESTIMATES OVER 200 PERCENT OF NORMAL
ALSO ASSOCIATED WITH THESE FEATURES. THIS IS RESULTING IN A SWATH
OF MODERATE TO HEAVY SNOW...ALSO BEING AIDED BY STRONG OROGRAPHIC
LIFT OVER THE WIND RIVER MOUNTAINS AND CASPER MOUNTAIN AS WELL AS
THE GREEN AND RATTLESNAKE RANGES AND THE OWL CREEK AND BRIDGER
MOUNTAINS. MODELS IN FAIR AGREEMENT WITH CONTINUED SNOWFALL
THROUGH THE NIGHT TAPERING OFF IN THE MORNING AS THE UPPER CUT OFF
LOW SINKS SOUTH INTO SOUTHWEST COLORADO. WINTER STORM WARNINGS IN
EFFECT FOR NATRONA...FREMONT AND HOT SPRINGS COUNTIES. AREAS NORTH
AND SOUTH OF THE HEAVY SNOW BAND ARE IN WINTER WEATHER ADVISORIES
TONIGHT. THE WESTERN LOCATIONS...THE GREEN RIVER BASIN...ABSAROKA
MOUNTAINS AND CODY FOOTHILL EXPECTED TO SEE SNOW TAPER OFF AROUND
MIDNIGHT AND ADVISORIES WILL END IN THESE LOCATIONS THEN. SNOWFALL
AROUND 15 INCHES IN THE WINDS AND CASPER MOUNTAINS SHOULD BE
WIDESPREAD WITH LOCAL 20 INCH AMOUNTS POSSIBLE. LANDER...CASPER
AND THERMOPOLIS SHOULD SEE AROUND 10 INCHES ON THE SOUTH SIDE OF
THESE TOWNS ADJACENT TO THE MOUNTAINS WITH DECREASING AMOUNTS AWAY
FROM THE MOUNTAINS. TEMPERATURES WILL BE COLD TONIGHT THROUGH
THURSDAY. PARTIAL CLEARING WILL OCCUR FROM NORTHWEST TO SOUTHEAST
THROUGH THURSDAY.

LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

BY THURSDAY NIGHT THE TWO JET STREAMS SPLIT...DEPOSITING OUR CURRENT
CUTOFF LOW IN BETWEEN THE TWO TRACKS AND LEAVING IT TO SIT AND SPIN
THERE FOR A FEW DAYS. AS THE UPPER LOW SPINS OVER COLORADO...IT WILL
KICK UP SOME MOISTURE AROUND THE LOW WHICH WILL CONTINUE THE
POTENTIAL FOR RAIN AND SNOW ACROSS EASTERN PORTIONS OF THE FORECAST
AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THIS BAND OF
PRECIPITATION WILL SET UP BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO AS FAR WEST AS FREMONT AND SWEETWATER COUNTIES. WE WILL
BE ON A SLOW WARMING TREND HOWEVER...SO MOST OF THIS PRECIPITATION
IS EXPECTED TO FALL AS RAIN.

THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE NORTHERN STORM
TRACK ALONG OUR BORDER WITH CANADA...THIS WILL EVENTUALLY SWING DOWN
ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED LOW TO FINALLY MOVE ON
INTO THE PLAINS. THIS KICKER SYSTEM COULD ENCOURAGE SOME SHOWERS AS
IT SWINGS ON THROUGH...WITH SOME SHOWERS CONTINUING INTO SUNDAY AS
THE COLD POOL ALOFT MOVES OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE
FOR ANOTHER DAY.

YET ANOTHER SHORT WAVE COULD MOVE AROUND THE BASE OF THE TROUGH ON
MONDAY...MOST OF THE ENERGY WITH THIS SYSTEM AT THIS TIME APPEARS TO
REMAIN TO OUR SOUTH BUT IT COULD AT LEAST DRAW DOWN ANOTHER COLD
FRONT ACROSS THE AREA. THERE IS SOME DISAGREEMENT IN THE MODEL
SOLUTIONS AFTER MONDAY ABOUT WHAT HAPPENS NEXT...ONE BUILDS A VERY
WEAK BUT SLIGHTLY WARMER RIDGE INTO THE REGION WHILE THE OTHER KEEPS
THE REGION WET AND UNSETTLED THROUGH MID WEEK. EITHER WAY...IT LOOKS
LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE RECORDS NEXT WEEK
AND WE COULD HAVE A FEW MORE CHANCES FOR SOME PRECIPITATION...WHICH
IS NOT TOO SURPRISING GIVEN THIS IS USUALLY THE WETTEST TIME OF THE
YEAR.

AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

SNOW WILL CONTINUE ACROSS CENTRAL WYOMING...ESPECIALLY ACROSS THE
KLND...KRIW...AND KCPR SITES...THIS EVENING AND LIKELY THROUGH THE
NIGHT. IFR CONDITIONS WILL BE LIKELY ACROSS AREAS WITH SNOW.
NORTHERN PORTIONS OF WYOMING WILL STILL SEE SCATTERED SNOW SHOWERS
AND TIMES OF IFR/MVFR CONDITIONS TONIGHT...WITH IMPROVING CONDITIONS
EXPECTED ACROSS THE NORTH LATE TONIGHT INTO THURSDAY MORNING. GUSTY
WINDS...PEAKING AROUND 30 TO 40 KNOTS...WILL ALSO BE POSSIBLE ACROSS MANY
TERMINALS THIS EVENING INTO THURSDAY MORNING. MOST AREAS WILL THEN
HAVE IMPROVING CONDITIONS THURSDAY AFTERNOON...WITH VFR CONDITIONS
LIKELY RETURNING TO ALL SITES. MOUNTAINS WILL ALSO REMAIN OBSCURED
THROUGH THE NIGHT.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

EXPECT SCATTERED AREAS OF SNOW TO OCCUR THIS EVENING...ESPECIALLY
ACROSS THE KBPI...KPNA...AND KRKS TERMINALS. MVFR/IFR CONDITIONS
WILL LIKELY OCCUR ACROSS AREAS WITH SNOW. MOUNTAINS WILL BE
FREQUENTLY BE OBSCURED THROUGH THIS EVENING. GUSTY WINDS WILL ALSO
BE FOUND ACROSS SOUTHERN PORTIONS...MAINLY NEAR THE KRKS TERMINAL.
ISOLATED VFR CONDITIONS WILL BEGIN TO OCCUR AT SOME OF THE TERMINAL
SITES LATER THIS EVENING...WITH WIDESPREAD VFR CONDITIONS RETURNING
THURSDAY MORNING. PLEASE SEE INDIVIDUAL TERMINAL SITES FOR MORE
DETAILS.

FIRE WEATHER...

SNOWFALL WILL BE RATHER WIDESPREAD TONIGHT COMING TO AN END ON
THURSDAY. SIGNIFICANT SNOWFALLS ARE EXPECTED IN FREMONT...HOT SPRINGS
AND NATRONA COUNTIES. LOWER SNOWFALL AMOUNTS ARE EXPECTED TO THE
NORTH AND SOUTH OF THESE COUNTIES. HIGH RELATIVE HUMIDITY AND COLD
TEMPERATURES WITH LOW MIXING HEIGHTS AND POOR SMOKE DISPERSAL WILL
ALSO OCCUR THROUGH THURSDAY. STRONG NORTHEAST WINDS WILL PRODUCE
AREAS OF BLOWING AND DRIFTING SNOW WITH NEAR ZERO VISIBILITY AT
TIMES TONIGHT AND EARLY THURSDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT THURSDAY
WYZ014-015-018>020-022.

&&

$$

UPDATE...AEM
SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER





000
FXUS65 KRIW 160601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1201 AM MDT THU APR 16 2015

.UPDATE...CANCELLED WINTER WX ADVISORY FOR EASTERN JOHNSON COUNTY
AND WINTER STORM WARNING FOR OWL CREEK AND BRIDGER MTNS...WHERE
SNOW HAD ENDED OR BECOME INTERMITTENT AND LIGHT.

&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VCNTY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VCNTY KCOD-KLND...THROUGH 12Z.  A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BTWN 12Z AND 16Z RESULTING IN
CIGS GRADUALLY LIFTING AND MOST -SN ENDING.  ANOTHER BATCH OF RAIN
AND SNOW SHOWERS MAY ROTATE WWD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS ACTIVITY
EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VCNTY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCNL MVFR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VCNTY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SFC WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VCNTY KRKS.


&&

.PREV DISCUSSION... /ISSUED 921 PM MDT WED APR 15 2015/

UPDATE...
CANCELLED WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR
PORTIONS OF CENTRAL WYOMING WHERE SNOW HAS ENDED OR BECOME VERY
LIGHT.

PREV DISCUSSION... /ISSUED 631 PM MDT WED APR 15 2015/

UPDATE...ALLOWED WINTER WEATHER ADVISORY TO EXPIRE FOR ZONE 12.
ALL OTHER WINTER STORM WARNINGS/ADVISORIES REMAIN IN EFFECT.
BAROCLINIC LEAF AND HEAVIER PRECIPITATION THAT STRETCHED FROM SE
WY INTO NORTH CENTRAL WY THIS AFTERNOON HAS DISSIPATED AS LARGER
STORMS FORMED OVER THE NEBRASKA PANHANDLE. MAINLY UPSLOPE FAVORED
AREAS...CASPER...LANDER AND ADJACENT MOUNTAINS...RECEIVING THE
HEAVIER SNOWFALL EARLY THIS EVENING.

PREV DISCUSSION... /ISSUED 238 PM MDT WED APR 15 2015/

SHORT TERM...TONIGHT THROUGH THURSDAY

UPPER LEVEL LOW CUT OFF IN FAVORABLE LOCATION BETWEEN VERNAL
UTAH AND GRAND JUNCTION COLORADO WITH TROUGH OF WARM AIR ALOFT
AND OCCLUSION OVER NATRONA AND FREMONT COUNTIES. THIS IS ALSO
ASSOCIATED WITH A JET STREAK PRODUCING STRONG UPPER DIVERGENCE.
STRONG FRONTOGENESIS OCCURRING WITH MID LEVEL DEFORMATION.
SATELLITE PRECIPITABLE WATER ESTIMATES OVER 200 PERCENT OF NORMAL
ALSO ASSOCIATED WITH THESE FEATURES. THIS IS RESULTING IN A SWATH
OF MODERATE TO HEAVY SNOW...ALSO BEING AIDED BY STRONG OROGRAPHIC
LIFT OVER THE WIND RIVER MOUNTAINS AND CASPER MOUNTAIN AS WELL AS
THE GREEN AND RATTLESNAKE RANGES AND THE OWL CREEK AND BRIDGER
MOUNTAINS. MODELS IN FAIR AGREEMENT WITH CONTINUED SNOWFALL
THROUGH THE NIGHT TAPERING OFF IN THE MORNING AS THE UPPER CUT OFF
LOW SINKS SOUTH INTO SOUTHWEST COLORADO. WINTER STORM WARNINGS IN
EFFECT FOR NATRONA...FREMONT AND HOT SPRINGS COUNTIES. AREAS NORTH
AND SOUTH OF THE HEAVY SNOW BAND ARE IN WINTER WEATHER ADVISORIES
TONIGHT. THE WESTERN LOCATIONS...THE GREEN RIVER BASIN...ABSAROKA
MOUNTAINS AND CODY FOOTHILL EXPECTED TO SEE SNOW TAPER OFF AROUND
MIDNIGHT AND ADVISORIES WILL END IN THESE LOCATIONS THEN. SNOWFALL
AROUND 15 INCHES IN THE WINDS AND CASPER MOUNTAINS SHOULD BE
WIDESPREAD WITH LOCAL 20 INCH AMOUNTS POSSIBLE. LANDER...CASPER
AND THERMOPOLIS SHOULD SEE AROUND 10 INCHES ON THE SOUTH SIDE OF
THESE TOWNS ADJACENT TO THE MOUNTAINS WITH DECREASING AMOUNTS AWAY
FROM THE MOUNTAINS. TEMPERATURES WILL BE COLD TONIGHT THROUGH
THURSDAY. PARTIAL CLEARING WILL OCCUR FROM NORTHWEST TO SOUTHEAST
THROUGH THURSDAY.

LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

BY THURSDAY NIGHT THE TWO JET STREAMS SPLIT...DEPOSITING OUR CURRENT
CUTOFF LOW IN BETWEEN THE TWO TRACKS AND LEAVING IT TO SIT AND SPIN
THERE FOR A FEW DAYS. AS THE UPPER LOW SPINS OVER COLORADO...IT WILL
KICK UP SOME MOISTURE AROUND THE LOW WHICH WILL CONTINUE THE
POTENTIAL FOR RAIN AND SNOW ACROSS EASTERN PORTIONS OF THE FORECAST
AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THIS BAND OF
PRECIPITATION WILL SET UP BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO AS FAR WEST AS FREMONT AND SWEETWATER COUNTIES. WE WILL
BE ON A SLOW WARMING TREND HOWEVER...SO MOST OF THIS PRECIPITATION
IS EXPECTED TO FALL AS RAIN.

THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE NORTHERN STORM
TRACK ALONG OUR BORDER WITH CANADA...THIS WILL EVENTUALLY SWING DOWN
ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED LOW TO FINALLY MOVE ON
INTO THE PLAINS. THIS KICKER SYSTEM COULD ENCOURAGE SOME SHOWERS AS
IT SWINGS ON THROUGH...WITH SOME SHOWERS CONTINUING INTO SUNDAY AS
THE COLD POOL ALOFT MOVES OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE
FOR ANOTHER DAY.

YET ANOTHER SHORT WAVE COULD MOVE AROUND THE BASE OF THE TROUGH ON
MONDAY...MOST OF THE ENERGY WITH THIS SYSTEM AT THIS TIME APPEARS TO
REMAIN TO OUR SOUTH BUT IT COULD AT LEAST DRAW DOWN ANOTHER COLD
FRONT ACROSS THE AREA. THERE IS SOME DISAGREEMENT IN THE MODEL
SOLUTIONS AFTER MONDAY ABOUT WHAT HAPPENS NEXT...ONE BUILDS A VERY
WEAK BUT SLIGHTLY WARMER RIDGE INTO THE REGION WHILE THE OTHER KEEPS
THE REGION WET AND UNSETTLED THROUGH MID WEEK. EITHER WAY...IT LOOKS
LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE RECORDS NEXT WEEK
AND WE COULD HAVE A FEW MORE CHANCES FOR SOME PRECIPITATION...WHICH
IS NOT TOO SURPRISING GIVEN THIS IS USUALLY THE WETTEST TIME OF THE
YEAR.

AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

SNOW WILL CONTINUE ACROSS CENTRAL WYOMING...ESPECIALLY ACROSS THE
KLND...KRIW...AND KCPR SITES...THIS EVENING AND LIKELY THROUGH THE
NIGHT. IFR CONDITIONS WILL BE LIKELY ACROSS AREAS WITH SNOW.
NORTHERN PORTIONS OF WYOMING WILL STILL SEE SCATTERED SNOW SHOWERS
AND TIMES OF IFR/MVFR CONDITIONS TONIGHT...WITH IMPROVING CONDITIONS
EXPECTED ACROSS THE NORTH LATE TONIGHT INTO THURSDAY MORNING. GUSTY
WINDS...PEAKING AROUND 30 TO 40 KNOTS...WILL ALSO BE POSSIBLE ACROSS MANY
TERMINALS THIS EVENING INTO THURSDAY MORNING. MOST AREAS WILL THEN
HAVE IMPROVING CONDITIONS THURSDAY AFTERNOON...WITH VFR CONDITIONS
LIKELY RETURNING TO ALL SITES. MOUNTAINS WILL ALSO REMAIN OBSCURED
THROUGH THE NIGHT.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

EXPECT SCATTERED AREAS OF SNOW TO OCCUR THIS EVENING...ESPECIALLY
ACROSS THE KBPI...KPNA...AND KRKS TERMINALS. MVFR/IFR CONDITIONS
WILL LIKELY OCCUR ACROSS AREAS WITH SNOW. MOUNTAINS WILL BE
FREQUENTLY BE OBSCURED THROUGH THIS EVENING. GUSTY WINDS WILL ALSO
BE FOUND ACROSS SOUTHERN PORTIONS...MAINLY NEAR THE KRKS TERMINAL.
ISOLATED VFR CONDITIONS WILL BEGIN TO OCCUR AT SOME OF THE TERMINAL
SITES LATER THIS EVENING...WITH WIDESPREAD VFR CONDITIONS RETURNING
THURSDAY MORNING. PLEASE SEE INDIVIDUAL TERMINAL SITES FOR MORE
DETAILS.

FIRE WEATHER...

SNOWFALL WILL BE RATHER WIDESPREAD TONIGHT COMING TO AN END ON
THURSDAY. SIGNIFICANT SNOWFALLS ARE EXPECTED IN FREMONT...HOT SPRINGS
AND NATRONA COUNTIES. LOWER SNOWFALL AMOUNTS ARE EXPECTED TO THE
NORTH AND SOUTH OF THESE COUNTIES. HIGH RELATIVE HUMIDITY AND COLD
TEMPERATURES WITH LOW MIXING HEIGHTS AND POOR SMOKE DISPERSAL WILL
ALSO OCCUR THROUGH THURSDAY. STRONG NORTHEAST WINDS WILL PRODUCE
AREAS OF BLOWING AND DRIFTING SNOW WITH NEAR ZERO VISIBILITY AT
TIMES TONIGHT AND EARLY THURSDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT THURSDAY
WYZ014-015-018>020-022.

&&

$$

UPDATE...AEM
SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER






000
FXUS65 KRIW 160601
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1201 AM MDT THU APR 16 2015

.UPDATE...CANCELLED WINTER WX ADVISORY FOR EASTERN JOHNSON COUNTY
AND WINTER STORM WARNING FOR OWL CREEK AND BRIDGER MTNS...WHERE
SNOW HAD ENDED OR BECOME INTERMITTENT AND LIGHT.

&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

WIDESPREAD MVFR AND AREAS OF IFR CONDITIONS IN -SN WILL CONTINUE TO
PREVAIL VCNTY AND SOUTH OF A KCPR-KRIW LINE AND ALONG THE EAST
SLOPES OF THE DIVIDE...VCNTY KCOD-KLND...THROUGH 12Z.  A DRIER
AIRMASS WILL ROTATE NW ACROSS THE AREA BTWN 12Z AND 16Z RESULTING IN
CIGS GRADUALLY LIFTING AND MOST -SN ENDING.  ANOTHER BATCH OF RAIN
AND SNOW SHOWERS MAY ROTATE WWD ACROSS SOUTHERN WYOMING LATE
THURSDAY AFTERNOON AND THURSDAY EVENING...WITH MOST OF THIS ACTIVITY
EXPECTED ALONG AND SOUTH OF A KCPR-KLND LINE THROUGH 12Z FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL VCNTY AND NORTH OF KJAC WHERE A N-NE
DOWNSLOPE WIND WILL PERSIST THROUGH THE PERIOD.  OCNL MVFR/IFR
CONDITIONS IN -SN WILL OCCUR ACROSS THE SW QUARTER OF WY...VCNTY AND
SOUTH OF KBPI...THROUGH THE PERIOD.  THE SNOW MAY BECOME MIXED WITH
RAIN THURSDAY AFTERNOON AND EVENING.  GUSTY NE SFC WINDS AT 25-35KTS
WILL CONTINUE ACROSS THE INTERSTATE 80 CORRIDOR...VCNTY KRKS.


&&

.PREV DISCUSSION... /ISSUED 921 PM MDT WED APR 15 2015/

UPDATE...
CANCELLED WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR
PORTIONS OF CENTRAL WYOMING WHERE SNOW HAS ENDED OR BECOME VERY
LIGHT.

PREV DISCUSSION... /ISSUED 631 PM MDT WED APR 15 2015/

UPDATE...ALLOWED WINTER WEATHER ADVISORY TO EXPIRE FOR ZONE 12.
ALL OTHER WINTER STORM WARNINGS/ADVISORIES REMAIN IN EFFECT.
BAROCLINIC LEAF AND HEAVIER PRECIPITATION THAT STRETCHED FROM SE
WY INTO NORTH CENTRAL WY THIS AFTERNOON HAS DISSIPATED AS LARGER
STORMS FORMED OVER THE NEBRASKA PANHANDLE. MAINLY UPSLOPE FAVORED
AREAS...CASPER...LANDER AND ADJACENT MOUNTAINS...RECEIVING THE
HEAVIER SNOWFALL EARLY THIS EVENING.

PREV DISCUSSION... /ISSUED 238 PM MDT WED APR 15 2015/

SHORT TERM...TONIGHT THROUGH THURSDAY

UPPER LEVEL LOW CUT OFF IN FAVORABLE LOCATION BETWEEN VERNAL
UTAH AND GRAND JUNCTION COLORADO WITH TROUGH OF WARM AIR ALOFT
AND OCCLUSION OVER NATRONA AND FREMONT COUNTIES. THIS IS ALSO
ASSOCIATED WITH A JET STREAK PRODUCING STRONG UPPER DIVERGENCE.
STRONG FRONTOGENESIS OCCURRING WITH MID LEVEL DEFORMATION.
SATELLITE PRECIPITABLE WATER ESTIMATES OVER 200 PERCENT OF NORMAL
ALSO ASSOCIATED WITH THESE FEATURES. THIS IS RESULTING IN A SWATH
OF MODERATE TO HEAVY SNOW...ALSO BEING AIDED BY STRONG OROGRAPHIC
LIFT OVER THE WIND RIVER MOUNTAINS AND CASPER MOUNTAIN AS WELL AS
THE GREEN AND RATTLESNAKE RANGES AND THE OWL CREEK AND BRIDGER
MOUNTAINS. MODELS IN FAIR AGREEMENT WITH CONTINUED SNOWFALL
THROUGH THE NIGHT TAPERING OFF IN THE MORNING AS THE UPPER CUT OFF
LOW SINKS SOUTH INTO SOUTHWEST COLORADO. WINTER STORM WARNINGS IN
EFFECT FOR NATRONA...FREMONT AND HOT SPRINGS COUNTIES. AREAS NORTH
AND SOUTH OF THE HEAVY SNOW BAND ARE IN WINTER WEATHER ADVISORIES
TONIGHT. THE WESTERN LOCATIONS...THE GREEN RIVER BASIN...ABSAROKA
MOUNTAINS AND CODY FOOTHILL EXPECTED TO SEE SNOW TAPER OFF AROUND
MIDNIGHT AND ADVISORIES WILL END IN THESE LOCATIONS THEN. SNOWFALL
AROUND 15 INCHES IN THE WINDS AND CASPER MOUNTAINS SHOULD BE
WIDESPREAD WITH LOCAL 20 INCH AMOUNTS POSSIBLE. LANDER...CASPER
AND THERMOPOLIS SHOULD SEE AROUND 10 INCHES ON THE SOUTH SIDE OF
THESE TOWNS ADJACENT TO THE MOUNTAINS WITH DECREASING AMOUNTS AWAY
FROM THE MOUNTAINS. TEMPERATURES WILL BE COLD TONIGHT THROUGH
THURSDAY. PARTIAL CLEARING WILL OCCUR FROM NORTHWEST TO SOUTHEAST
THROUGH THURSDAY.

LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

BY THURSDAY NIGHT THE TWO JET STREAMS SPLIT...DEPOSITING OUR CURRENT
CUTOFF LOW IN BETWEEN THE TWO TRACKS AND LEAVING IT TO SIT AND SPIN
THERE FOR A FEW DAYS. AS THE UPPER LOW SPINS OVER COLORADO...IT WILL
KICK UP SOME MOISTURE AROUND THE LOW WHICH WILL CONTINUE THE
POTENTIAL FOR RAIN AND SNOW ACROSS EASTERN PORTIONS OF THE FORECAST
AREA. IT IS UNCERTAIN EXACTLY HOW FAR WEST THIS BAND OF
PRECIPITATION WILL SET UP BUT IT WILL LIKELY REMAIN NEAR THE I25
CORRIDOR TO AS FAR WEST AS FREMONT AND SWEETWATER COUNTIES. WE WILL
BE ON A SLOW WARMING TREND HOWEVER...SO MOST OF THIS PRECIPITATION
IS EXPECTED TO FALL AS RAIN.

THERE WILL BE A KICKER SYSTEM COMING DOWN FROM THE NORTHERN STORM
TRACK ALONG OUR BORDER WITH CANADA...THIS WILL EVENTUALLY SWING DOWN
ON SATURDAY AND ENCOURAGE OUR RESIDENT CLOSED LOW TO FINALLY MOVE ON
INTO THE PLAINS. THIS KICKER SYSTEM COULD ENCOURAGE SOME SHOWERS AS
IT SWINGS ON THROUGH...WITH SOME SHOWERS CONTINUING INTO SUNDAY AS
THE COLD POOL ALOFT MOVES OVERHEAD...KEEPING THE ATMOSPHERE UNSTABLE
FOR ANOTHER DAY.

YET ANOTHER SHORT WAVE COULD MOVE AROUND THE BASE OF THE TROUGH ON
MONDAY...MOST OF THE ENERGY WITH THIS SYSTEM AT THIS TIME APPEARS TO
REMAIN TO OUR SOUTH BUT IT COULD AT LEAST DRAW DOWN ANOTHER COLD
FRONT ACROSS THE AREA. THERE IS SOME DISAGREEMENT IN THE MODEL
SOLUTIONS AFTER MONDAY ABOUT WHAT HAPPENS NEXT...ONE BUILDS A VERY
WEAK BUT SLIGHTLY WARMER RIDGE INTO THE REGION WHILE THE OTHER KEEPS
THE REGION WET AND UNSETTLED THROUGH MID WEEK. EITHER WAY...IT LOOKS
LIKE WE WILL NOT BE BREAKING ANY HIGH TEMPERATURE RECORDS NEXT WEEK
AND WE COULD HAVE A FEW MORE CHANCES FOR SOME PRECIPITATION...WHICH
IS NOT TOO SURPRISING GIVEN THIS IS USUALLY THE WETTEST TIME OF THE
YEAR.

AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

SNOW WILL CONTINUE ACROSS CENTRAL WYOMING...ESPECIALLY ACROSS THE
KLND...KRIW...AND KCPR SITES...THIS EVENING AND LIKELY THROUGH THE
NIGHT. IFR CONDITIONS WILL BE LIKELY ACROSS AREAS WITH SNOW.
NORTHERN PORTIONS OF WYOMING WILL STILL SEE SCATTERED SNOW SHOWERS
AND TIMES OF IFR/MVFR CONDITIONS TONIGHT...WITH IMPROVING CONDITIONS
EXPECTED ACROSS THE NORTH LATE TONIGHT INTO THURSDAY MORNING. GUSTY
WINDS...PEAKING AROUND 30 TO 40 KNOTS...WILL ALSO BE POSSIBLE ACROSS MANY
TERMINALS THIS EVENING INTO THURSDAY MORNING. MOST AREAS WILL THEN
HAVE IMPROVING CONDITIONS THURSDAY AFTERNOON...WITH VFR CONDITIONS
LIKELY RETURNING TO ALL SITES. MOUNTAINS WILL ALSO REMAIN OBSCURED
THROUGH THE NIGHT.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

EXPECT SCATTERED AREAS OF SNOW TO OCCUR THIS EVENING...ESPECIALLY
ACROSS THE KBPI...KPNA...AND KRKS TERMINALS. MVFR/IFR CONDITIONS
WILL LIKELY OCCUR ACROSS AREAS WITH SNOW. MOUNTAINS WILL BE
FREQUENTLY BE OBSCURED THROUGH THIS EVENING. GUSTY WINDS WILL ALSO
BE FOUND ACROSS SOUTHERN PORTIONS...MAINLY NEAR THE KRKS TERMINAL.
ISOLATED VFR CONDITIONS WILL BEGIN TO OCCUR AT SOME OF THE TERMINAL
SITES LATER THIS EVENING...WITH WIDESPREAD VFR CONDITIONS RETURNING
THURSDAY MORNING. PLEASE SEE INDIVIDUAL TERMINAL SITES FOR MORE
DETAILS.

FIRE WEATHER...

SNOWFALL WILL BE RATHER WIDESPREAD TONIGHT COMING TO AN END ON
THURSDAY. SIGNIFICANT SNOWFALLS ARE EXPECTED IN FREMONT...HOT SPRINGS
AND NATRONA COUNTIES. LOWER SNOWFALL AMOUNTS ARE EXPECTED TO THE
NORTH AND SOUTH OF THESE COUNTIES. HIGH RELATIVE HUMIDITY AND COLD
TEMPERATURES WITH LOW MIXING HEIGHTS AND POOR SMOKE DISPERSAL WILL
ALSO OCCUR THROUGH THURSDAY. STRONG NORTHEAST WINDS WILL PRODUCE
AREAS OF BLOWING AND DRIFTING SNOW WITH NEAR ZERO VISIBILITY AT
TIMES TONIGHT AND EARLY THURSDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY
WYZ008-009-028-030.

WINTER STORM WARNING UNTIL 6 AM MDT THURSDAY
WYZ014-015-018>020-022.

&&

$$

UPDATE...AEM
SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...AEM
FIRE WEATHER...C.BAKER





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