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000
FXUS65 KCYS 300345 CCA
AFDCYS

Area Forecast Discussion...Corrected Update
National Weather Service Cheyenne WY
934 PM MDT SUN MAY 29 2016

.UPDATE...
Issued at 930 PM MDT Sun May 29 2016

Recent radar trends indicated convection quickly dissipating or
exiting east of the CWA at mid-evening. Updated grids to remove
pops from Nebraska Panhandle and mountain zones.

&&

.SHORT TERM...(This evening through Tuesday Night)
Issued at 210 PM MDT Sun May 29 2016

Scattered showers and some storms moving generally ENE across the
southeast half of the CWA this afternoon. Expect these to
continue into the evening hours before dissipating as instability
is lost with evening cooling. Quiet weather overnight under partly
cloudy skies.

An upper shortwave over the pacific NW will move generally east
along the US/Canadian border overnight and Monday and close off an
upper low over northeast Montana by evening. A surface low will
develop over western South Dakota with an attendant trough
extending south across the Nebraska Panhandle. This trough will
move east during the day and should help to focus some strong
convection along it. Currently appears this trough will be just
east of the CWA Monday afternoon with CAPES in excess of 1000 J/kg
progged to remain east of the Panhandle Monday so severe storm
threat in out area looks to be low with shear and instability
relatively modest. Still should see some showers and a few storms
Monday into Monday night as the upper low drifts slowly east and a
lobe of vorticity shifts across the northern high plains. A cool
front will move across the CWA Monday night bringing some cooling
for Tuesday. Still some convection possible Tuesday but it should
be confined to areas over se WY near the Colorado border. Dry and
cool Tuesday night with a surface high settling over Wy.

.LONG TERM...(Wednesday through Saturday Night)
Issued at 241 PM MDT Sun May 29 2016

The main story in the long term period is the trend towards
warmer and drier weather. An omega block pattern will develop
over the western CONUS Wed-Thurs and looks to persist through the
weekend. Broad-scale subsidence within the ridge will keep
convection to a minimum but could see isolated showers/storms in
the afternoon over the mountains. 700mb temps will steadily rise
through the latter part of the week with readings on average of 8
to 10C likely through Friday, and increasing further for
Saturday. Main concern as we approach the weekend continues to be
increase in snowmelt rates in the higher mountain elevations, and
resultant rises in river levels across the forecast area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 525 PM MDT Sun May 29 2016

VFR prevails. Isolated thunderstorms at all sites except Chadron
through 02z-03z this evening producing gusts to 30 knots. Isolated
thunderstorms again Monday afternoon.


&&

.FIRE WEATHER...
Issued at 241 PM MDT Sun May 29 2016

Concerns to remain minimal for at least the next few days as
conditions and fuels remain non-critical. A cool front will move
across the area Monday night keeping temperatures mild through
Tuesday. warmer and mainly dry weather should arrive on Weds and
persist for the rest of the week.

&&

.HYDROLOGY...
Issued at 241 PM MDT Sun May 29 2016

The North Platte and Laramie Rivers will continue to run high,
but remain steady or slowly recede over the next couple of days.
The exception will be areas that receive moderate rainfall today
and Monday which could produce short-term rises in river levels.
Warmer temperatures mid to late week will increase snowmelt once
again. Therefore, expect rises on area rivers, creeks and streams
by next weekend.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

UPDATE...MAJ
SHORT TERM...RE
LONG TERM...RJM
AVIATION...RUBIN
FIRE WEATHER...RE
HYDROLOGY...RJM/MAJ



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000
FXUS63 KUNR 292315
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
515 PM MDT SUN MAY 29 2016

.SHORT TERM...(This Evening Through Monday Night)
Issued at 225 PM MDT Sun May 29 2016

20Z sfc analysis shows high pressure over the eastern two-thirds
of the dakotas and nebraska with weak low pressure to the east of
the Rockies. Upper analysis shows a few wiggles in mainly zonal
flow aloft over the northern plains.

Diurnal heating and sfc dewpoints ranging from 40-50F have
increased the MUCAPE to 500-1500J/KG over parts of northeastern WY
and western SD. Scattered thunderstorms have develop over nwrn SD,
far nern WY and the Black Hills this afternoon. 0-6km bulk shear
is around 15-20m/s indicating that isolated strong to severe
storms are possible during the rest of the aftn and into the early
evening with large hail the main threat. An upper low will drop
southward out of Alberta and into nwrn Montana later tonight
causing a sfc low to develop over south central MT/north central
WY. A low level jet will develop to the east of the sfc low
increasing low and mid level Theta-e advection and thunderstorm
chances mainly over central South Dakota later tonight.

On Monday, the upper low will dip into eastern Montana as it
strengthens. The surface low will also deepen slightly as it
moves from western into central South Dakota. A relatively weak frontal
boundary will connect with the low later in the day with notable
return flow to the east of the boundary. Dew points in the 50s
pool east of the boundary creating 1-2KJ/kg MLCAPE by afternoon.
0-6km bulk shear will increase to 15-20m/s. The wild card is any
ongoing convection from Sunday night and it`s effect on surface
features. If sustained heating occurs ahead of the low, suspect
severe thunderstorms will develop by afternoon and then shift
southeastward Monday evening. Large hail and damaging winds will
be possible. As the surface low pushes east of the forecast area,
models advertise substantial frontal push, pressure rises, and a
short period of gusty northwest winds on monday night.

.LONG TERM...(Tuesday Through Sunday)
Issued at 225 PM MDT Sun May 29 2016

As the upper low passes through the Dakotas, chances
for showers/storms continue on Tuesday, mainly across northwestern
SD, the Black Hills, and portions of northeastern WY. Cooler
temperatures in the 60s, along with breezy northwest winds, are
expected for Tuesday into Wednesday. Other than some isolated
showers/storms over the Hills, the second half of the week looks
dry.  A warming trend is also expected, with temperatures climbing
into the 80s by Friday.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 512 PM MDT Sun May 29 2016

Isolated thunderstorms will diminish around sunset. Local MVFR
conditions will be possible with the precipitation. Strong to
severe thunderstorms will move across the area Monday afternoon.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...10
LONG TERM...13
AVIATION...7




000
FXUS63 KUNR 292046
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
246 PM MDT SUN MAY 29 2016

.SHORT TERM...(This Evening Through Monday Night)
Issued at 225 PM MDT Sun May 29 2016

20Z sfc analysis shows high pressure over the eastern two-thirds
of the dakotas and nebraska with weak low pressure to the east of
the Rockies. Upper analysis shows a few wiggles in mainly zonal
flow aloft over the northern plains.

Diurnal heating and sfc dewpoints ranging from 40-50F have
increased the MUCAPE to 500-1500J/KG over parts of northeastern WY
and western SD. Scattered thunderstorms have develop over nwrn SD,
far nern WY and the Black Hills this afternoon. 0-6km bulk shear
is around 15-20m/s indicating that isolated strong to severe
storms are possible during the rest of the aftn and into the early
evening with large hail the main threat. An upper low will drop
southward out of Alberta and into nwrn Montana later tonight
causing a sfc low to develop over south central MT/north central
WY. A low level jet will develop to the east of the sfc low
increasing low and mid level Theta-e advection and thunderstorm
chances mainly over central South Dakota later tonight.

On Monday, the upper low will dip into eastern Montana as it
strengthens. The surface low will also deepen slightly as it
moves from western into central South Dakota. A relatively weak frontal
boundary will connect with the low later in the day with notable
return flow to the east of the boundary. Dew points in the 50s
pool east of the boundary creating 1-2KJ/kg MLCAPE by afternoon.
0-6km bulk shear will increase to 15-20m/s. The wild card is any
ongoing convection from Sunday night and it`s effect on surface
features. If sustained heating occurs ahead of the low, suspect
severe thunderstorms will develop by afternoon and then shift
southeastward Monday evening. Large hail and damaging winds will
be possible. As the surface low pushes east of the forecast area,
models advertise substantial frontal push, pressure rises, and a
short period of gusty northwest winds on monday night.

.LONG TERM...(Tuesday Through Sunday)
Issued at 225 PM MDT Sun May 29 2016

As the upper low passes through the Dakotas, chances
for showers/storms continue on Tuesday, mainly across northwestern
SD, the Black Hills, and portions of northeastern WY. Cooler
temperatures in the 60s, along with breezy northwest winds, are
expected for Tuesday into Wednesday. Other than some isolated
showers/storms over the Hills, the second half of the week looks
dry.  A warming trend is also expected, with temperatures climbing
into the 80s by Friday.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 225 PM MDT Sun May 29 2016

Scattered showers and thunderstorms will redevelop this
afternoon and early evening, then diminish after sunset. Local MVFR
conditions will be possible with the precipitation.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...10
LONG TERM...13
AVIATION...13




000
FXUS63 KUNR 291035
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
435 AM MDT SUN MAY 29 2016

.SHORT TERM...(Today Through Monday Night)
Issued at 238 AM MDT Sun May 29 2016

08z surface analysis had low pressure over northwest MN with
frontal boundary into southeast WY. Upper low spinning above low
over northern MN. Very subtle shortwave noted in water vapour over
north central WY assisting some ACCAS and isolated thunderstorms
over northeast WY early this morning. No guidance depicts the
evolution of this wave, so winged it early this morning with
activity dying off shortly after sunrise. Concern for next two
days is upper trough and low over southwest Canada.

Today, southwest Canada system slips east with weak shortwave
ridging over the CWA. Return flow modest at best, so instability by
this afternoon will be weak - around 500J/kg MLCAPE and 25J/kg
MLCIN. Suspect aforementioned subtle shortwave will have an impact
on today`s convection, but confidence low on what it will be.
Shortwave ridge behind it should tend to suppress activity, but
storms will poke through MLCIN over the Black Hills with outflow
kicking off additional low coverage convection across the plains
late. 0-6km bulk shear around 15m/s so a strong storm or two is
possible. Temperatures will be near guidance.

Tonight, upper low sinks into northwest MT with surface low
developing over central WY. Low level jet develops ahead of system
with resultant 850-700mb theta-e advection and thunderstorm chances.
Temperatures will be near guidance.

Monday, upper low slides east into western ND by 12z Tuesday.
Surface low deepens slightly as it moves into west central SD. Weak
frontal boundary connects with low later in the day with notable
return flow ahead of it. Dew points in the 50s pool creating
1-2KJ/kg MLCAPE by afternoon. 0-6km bulk shear 15-20m/s. Wild card
is any ongoing convection from Sunday night and it`s effect on
surface features. If sustained heating occurs ahead of low,
suspect severe thunderstorms will pop up by late afternoon and
then shift southeast Monday evening. Large hail and damaging winds
possible. As the surface low pushes east of the CWA, models
advertise substantial frontal push, pressure rises, and a short
period of gusty northwest winds. Temperatures will be below
guidance in the west and above guidance in the east.

.LONG TERM...(Tuesday Through Saturday)
Issued at 238 AM MDT Sun May 29 2016

As the upper low passes through the Dakotas, chances for
showers/storms continue on Tuesday, mainly across northwestern SD,
the Black Hills, and portions of northeastern WY. Cooler
temperatures in the 60s, along with breezy northwest winds, are
expected for Tuesday into Wednesday. Other than some isolated
showers/storms over the Hills, the second half of the week looks
dry. A warming trend is also expected, with temperatures climbing
into the 80s by Friday.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Monday Morning)
Issued At 434 AM MDT Sun May 29 2016

VFR conditions are expected through this morning.
Isolated to scattered showers and thunderstorms this afternoon and
evening may result in local MVFR visibility.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...Helgeson
LONG TERM...Pojorlie
AVIATION...Pojorlie




000
FXUS65 KCYS 282329
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
529 PM MDT SAT MAY 28 2016

.SHORT TERM...(This evening through Monday Night)
Issued at 249 PM MDT Sat May 28 2016

Some showers and storms moving east across mainly the northern
parts of the CWA this afternoon but low shear and modest
instability keeping them fairly benign. Expect this activity to
diminish this evening as the boundary layer cools and instability
falls off.

No major changes in the overall weather pattern seen across the
area through Monday with a weak upper low over moving slowly east
over the desert SW and a stronger upper low that should move to
the Montana/southern Canadian border on Monday. Weak impulses
will move across the CWA in a generally westerly upper flow and
combine with instability to produce scattered mainly afternoon and
evening convection. Somewhat better shear and instability expected
across the northern parts of the CWA Monday as the upper low moves
a little closer so some stronger storms a better bet on that day
in that area. Otherwise temperatures seasonal over the next couple
days.

.LONG TERM...(Tuesday through Friday Night)
Issued at 249 PM MDT Sat May 28 2016

Models remain in agreement with swinging an upper level trough
across the high plains on Tuesday and Tuesday night, while surface
high pressure builds in from the west. The attendant cold front
is expected to be through our forecast area to the south by
Tuesday morning, so forcing for any ascent will be focused along
the Laramie Range and higher mountain peaks in upslope flow, and
where best instability will occur with cooler air aloft. High
pressure at the surface and a building ridge overhead will limit
convection for Wednesday although there remains a low chance for a
weak shower/storm over the higher peaks. Similar conditions will
persist for Thursday and Friday, while temps warm with the upper
ridge moving overhead. Could begin to see an increase in snowmelt
at this time, thus will have to monitor rivers closely for
potential rises.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 527 PM MDT Sat May 28 2016

VFR prevails. Isolated thunderstorms through 02Z producing
localized MVFR and gusty and erratic winds. Areas of IFR from 09Z
to 14Z in fog and low clouds at Chadron, Alliance and Scottsbluff.
Isolated thunderstorms again Sunday afternoon.

&&

.FIRE WEATHER...
Issued at 249 PM MDT Sat May 28 2016

Fire weather concerns to remain low into the early part of next
week with non-critical conditions continuing. There will be
widely scattered mainly afternoon and evening showers and
thunderstorms into early next week with wetting rains from some of
these.

&&

.HYDROLOGY...
Issued at 249 PM MDT Sat May 28 2016

The North Platte and Laramie Rivers continue to run high but
should remain steady or continue to slowly decline over the next
couple of days with relatively steady reservoir releases and with a
cool environment in place. Warmer temperatures next week will
begin to increase snow melt again...so rivers will be on the rise.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

SHORT TERM...RE
LONG TERM...RJM
AVIATION...RUBIN
FIRE WEATHER...RE
HYDROLOGY...RJM



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000
FXUS65 KRIW 281636
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1036 AM MDT SAT MAY 28 2016

.SHORT TERM...Today through Monday night

Imagery shows large trof across the western CONUS with a ridge
across the east and an embedded sw trof over the cntrl plains.
Another small embedded sw currently located ovr s cntrl MT. Surface
has general weak low pressure across WY with a weakening slow moving
front off to the west and a slightly more mobile portion of the same
front moving through cntrl MT. Tonight/this morning, isolated
showers/thunder from north to south across cntrl Wyoming.

Today, surface low develops weakly across southeastern WY with
boundary stretching back across the southern portion of the state
while the front currently across MT swings through northern/eastern
WY mainly as a clipper. Flow aloft becomes nearly zonal to slightly
southwesterly. Most precipitation will occur around the front or the
mountains of northern Wyoming and the boundary/weak front across the
south. Showers/storms will be of low CAPE, modest shear, low QPF,
very small hail (if any) and gusty wind variety with little chance
for any severe parameters to be met. Tonight, skies clear quickly
after sunset.

Sunday, flow remains modest and rather flat aloft while some weak
moisture tries to infiltrate the southern portion of WY. Most
convective precipitation will be isolated to widely scattered
afternoon based, centered around the area of moisture across south
and southwest WY. The western/southwestern mountains will stand the
best chance of seeing measurable precipitation - with a few spots in
the Salt and Wyoming ranges to perhaps the southern Tetons getting
up to a tenth of an inch of rainfall. Very small hail and gusty
winds will be the usual form of accompaniment to the relatively
sparse rainfall. Stronger storms of the day will be near the western
border areas with ID/UT. Sunday night into Monday, another weak sw
trof will move across WY from west to east with a few spurious light
showers continuing overnight into/through the Monday morning hours.

Monday, lee side troffing across eastern Wyoming will be quickly
followed by the formation of a modest surface cyclone across the
high/cntrl plains with rapid frontogenesis occuring across
southern/southeastern MT. A couple of clipper fronts will then move
to the south across nrn/cntrl/ern Wyoming in the afternoon and
evening. Another area of low pressure will occur further south ovr
nern NM/sern CO. This will give a maximum in convergence between the
two systems across sern WY/nern CO and to the east of this area.
This will also be the region that will see most of the severe
stormsof the day. The second clipper will push through the nrn and
ern portions of the forecast area through the late afternoon/evening
period. Showers/storms will accompany this front with gusty winds
and small hail a possibility for the most part. However, a severe
storm or two will be possible near this front in the afternoon/early
evening across Johnson county and points eastward, with large hail
and strong wind the main threat within these rotating storms. There
will also be a low chance for a brief tornado with this(these)
storm(s) near to just behind the front late in the afternoon/early
evening as LCLs drop quickly and these storms have their best
chance at becoming surface based.

.LONG TERM...Tuesday Through Friday

Synopsis...an upper level low pressure system will drift east across
the northern high plains Tuesday with some rain and mountain snow
showers wrapping back across northern Wyoming in cool northerly
flow.  A ridge of high pressure will build into the area Wednesday
and Thursday bringing a warming trend with summer-like temperatures
5-10F above normal expected Friday into next weekend.

Discussion...GFS and ECMWF in better agreement with track of upper
low into the northern plains on Tuesday with both placing the H5 low
center near the MT/ND/SD triple point 12z Tuesday, drifting east
across southern North Dakota during the day.  An overall trend of
placing wraparound precipitation further to the north and east will
place mainly the Bighorn Range in line for the best chances of
receiving accumulating snowfall on order of 3 to 5 inches from
Powder River Pass and northward Tuesday morning with snow levels
near 7500 feet. The best chances for valley rain showers will be
along and north of a Cody to Buffalo line.  A brisk northerly wind
will develop Tuesday afternoon east of the divide with highs mostly
in the 50s to lower 60s.

A ridge of high pressure will then bring a more summer-like pattern
to the area Thursday through Saturday with a few afternoon
thunderstorms developing along mountain/valley breeze boundaries,
mainly along eastern slopes.  Warming mountain temperatures will
accelerate the melting of remaining mountain snowpack above 9000
feet with corresponding rises in creeks and rivers expected.

&&

.AVIATION.../18Z ISSUANCE/

West of the Continental Divide...KJAC/KRKS/KPNA/KBPI Routes

Isolated showers and storms over northwest WY through early
evening. Local mvfr cigs/vsbys are possible with storms. In
southern WY this afternoon isolated showers and storms will occur
into the early evening. KRKS airport will be close to this
activity and VCSH will be included in the TAF. Otherwise VFR
conditions to prevail over the region through tonight. Isolated to
widely scattered showers and thunderstorms will move back into the
KBPI, KPNA, KJAC and KRKS area Sunday afternoon.

East of the Continental Divide...KCPR/KCOD/KRIW/KWRL/KLND Routes

Isolated showers and thunderstorms will continue into the evening
hours along and east of a line from near KCOD down to KCPR.
MVFR cigs/vsbys will be likely with storms thru 02z. Otherwise,
VFR conditions will prevail over the rest of the area today and
tonight. Isolated mainly mountain showers or thunderstorms are
possible Sunday afternoon.

&&

.FIRE WEATHER...

Fire danger low today and Sunday as green-up and seasonally elevated
humidity levels continue across Wyoming. Isolated to widely
scattered showers and storms possible by mid-day through the early
evening period across mainly northern, eastern and southern Wyoming
with little overall rainfall expected with any of this activity and
less than a tenth of an inch of precipitation at the best locations
in the Bighorn Mountains. Winds will flow out of the west to
southwest west of the Divide at 10 to 20 mph, but will be light and
variable to the east. Sunday will see the warmest temperatures of
the weekend with a few locations in the Wind River and Bighorn
Basins seeing RH values drop into the the upper teens (percent).
Winds across the entire forecast area will be on the light side.

&&

.RIW Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...Braun
LONG TERM...AEM
AVIATION...PS
FIRE WEATHER...Braun




000
FXUS65 KCYS 281131
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
531 AM MDT SAT MAY 28 2016

.SHORT TERM...(Today through Monday)
Issued at 300 AM MDT Sat May 28 2016

Unsettled weather will continue in the short term as we stay under
northwest flow.

Currently...Water vapor imagery showing trough of low pressure
across the Rockies into southern california. No big changes from
what we have been seeing the past week or so. Shortwave moving
into western Wyoming this morning will be the kicker for more
showers and thunderstorms later today.

Not looking at anything severe today. Both the GFS and NAM
forecasting 500-600 J/KG Capes. Not a lot of upper level jet
support either for thunderstorms...so am not too concerned with
anything severe today or Sunday. Sunday may be our driest day as
we get brief ridging over the area.

Monday may be the severe day as a cold front moves through the
area. SPC has a Slight Risk area identified for the Panhandle and
western South Dakota. Capes on the order of 2000 to 2500 J/KG out
that way as the nose of a 80kt jet moves into the area.

.LONG TERM...(Monday Night through Friday)
Issued at 300 AM MDT Sat May 28 2016

An upper-level trough will continue to move slowly eastward across
the CWA through at least Wed. Isolated to widely scattered showers
and thunderstorms will be the result, before large scale upper-lvl
ridging builds in for mid/late week. Subsidence aloft should limit
precipitation chances after Wednesday, although the GFS/ECMWF both
hint at weak disturbances undercutting the ridge which could yield
off and on precipitation chances in the mountains. A warming trend
can be expected through the period as H7 temperatures climb to +10
to +12 deg C by Fri/Sat.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 526 AM MDT Sat May 28 2016

Patchy fog is occurring early this am over portions of the western
Nebraska Panhandle. There will be the potential for periods of IFR
or LIFR visibilities at KCDR, KAIA, and KBFF through 15z. Isolated
to widely scattered thunderstorms will develop this afternoon, and
spread across the CWA later today. Strong/severe thunderstorms are
not expected.

&&

.FIRE WEATHER...
Issued at 300 AM MDT Sat May 28 2016

Minimal fire weather concerns with greenup well underway and with
many areas seeing wetting rains the next few days. Afternoon
humidities expected to be well above critical levels with good to
excellent overnight recoveries.

&&

.HYDROLOGY...
Issued at 140 AM MDT Sat May 28 2016

Area rivers continue to run high...but are showing signs of
decreasing. Reservoir releases will keep the North Platte River
in the Panhandle and Laramie River at Fort Laramie running at
Flood stage. WArmer temperatures next week will begin to increase
snow melt again...so rivers will be on the rise across the Upper
North Platte and Laramie River at Laramie next week.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

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




000
FXUS65 KRIW 280505
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1105 PM MDT FRI MAY 27 2016

.SHORT TERM...TONIGHT THROUGH MONDAY (issued at 359 PM MDT)

AN EXITING WELL DEVELOPED COLD LOW OVER EASTERN COLORADO WILL
CONTINUE TO EXIT TO THE EAST. THE NEXT SIGNIFICANT UPPER LOW
EXISTS OVER SOUTHERN BRITISH COLUMBIA WITH A SLIGHTLY NEGATIVELY
TILTED TROUGH EXTENDING TO THE SOUTH OF THERE. WESTERN AND CENTRAL
WYOMING LIES BETWEEN THESE TWO LOW CENTERS WITH THE
AFOREMENTIONED TROUGH DRIVING A WEAK VORT EASTWARD NOW SITUATED
ALONG THE MONTANA IDAHO BORDER. WITHOUT MUCH FORCING FROM THESE
TWO MAIN FEATURES... WE ARE RELYING Solely ON WEAK CAPE/LIFTED
INDICES AND WEAK WESTERLY DIFLUENT FLOW ALOFT TO PRODUCE MOSTLY
CONTINUED WEAK CONVECTION FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING. MOST OF THESE CELLS HAVE HAD A TOUGH TIME BREAKING AWAY
FROM THE MOUNTAINS WHERE THEY FORMED DUE TO FORCED ASCENT. SOME OF
THE TINY MORE ENHANCED CELLS HAVE MANAGED TO PRODUCE SMALL HAIL.
THE AFOREMENTIONED VORT LOBE IS HELPING TO A DEGREE. ANOTHER
TROUGH WILL SWING BY ON SATURDAY WITH SIMILAR RESULTS, WITH THE
BEST INSTABILITY WEST OF THE DIVIDE. SUNDAY WILL BE THE WARMEST
AND DRIEST DAY OF THE HOLIDAY WEEKEND AS HEIGHTS RISE AHEAD OF THE
APPROACHING CLOSED LOW THAT WILL GET DISLODGED FROM SOUTHERN
BRITISH COLUMBIA AND WILL COME SCOOTING ACROSS MONTANA MEMORIAL
DAY/MONDAY. THE ONLY CONVECTION EXPECTED SUNDAY WILL BE MOSTLY IN
THE SOUTHWEST AND NORTHEAST ZONES. THIS CLOSED LOW WILL SWING A
PROMINENT TROUGH ACROSS THE STATE FROM WEST TO EAST ACROSS
WYOMING, COMPLETE WITH A TIGHT THERMAL GRADIENT. DRIER AIR WILL
BE PUNCHING BEHIND THE TROUGH WITH MUCH HIGHER CAPES OVER THE
EASTERN ZONES WHERE THE BEST CHANCE OF ANY STRONG THUNDERSTORMS
WILL BE. HOWEVER...A BETTER CHANCE OF THUNDERSTORMS EXISTS
THROUGHOUT THE AREA...ESPECIALLY UP NORTH. THE SNOW LEVEL WILL
LIKELY DROP TO 8K IN THE NORTHERN MTNS BY THE LATTER PORTION OF
MEMORIAL DAY.


.LONG TERM...MONDAY NIGHT THROUGH FRIDAY

Main issue with the forecast is generally at the beginning of the
period in regards to where our next upper low will be Monday night
and Tuesday. The GFS is furthest south with a majority of the trough
swinging across the north half of the forecast area. The ECMWF is
furthest north in Nrn MT/Southern Canada (but trending south again)
and the GEM is about in the middle. Longer wave analysis would
support a further south solution so will keep the going forecast
unchanged. With that said, there is enough cold air to bring a quick
shot of snow to the nrn mtns Monday night. After that, the mean
ridge begins to build into the region with warming temps. Models are
trying to keep the ridge somewhat dirty with moisture spilling se
down the front side of the ridge, mainly Thursday into Friday. Going
forecast already had that handled with some isold storms in the nrn
mtns trying to spill se of the foothills late in the day. No reason
to change this.

&&

.AVIATION.../06Z ISSUANCE/

West of the Continental Divide...KJAC/KRKS/KPNA/KBPI Routes

Isolated showers over the northwest through Saturday morning. Then
isolated showers and storms over far north WY Saturday afternoon
into early evening. Local mvfr cigs/vsbys are possible with storms.
In southern WY Saturday afternoon isolated showers and storms will
occur into the early evening. KRKS airport will be close to this
activity and VCSH will be included in the TAF. Otherwise VFR
conditions to prevail over the region through Saturday evening.

East of the Continental Divide...KCPR/KCOD/KRIW/KWRL/KLND Routes

Isolated showers will end by 12z in the eastern part of the area,
mainly from KBYG to KCPR. New showers and storms will develop by 18z
over the Bighorn Mountains southward to Casper. This activity will
occur through 00z Sunday and then diminish by 02z. MVFR cigs/vsbys
will be likely with storms from 18z Sat to 01z Sun. Otherwise, VFR
conditions will prevail over the rest of the area Saturday and
Saturday evening.

&&

.FIRE WEATHER...

A slow drying and warming trend will take place through the weekend.
Temperatures will slowly warm with relative humidity lowering each
day. There will still be some mainly afternoon and evening showers
and thunderstorms around, especially in and adjacent to the
mountains. Any thunderstorm could have erratic winds. Otherwise,
winds should remain light to moderate outside of showers or
thunderstorms. Coverage of thunderstorms will shrink each day with
many of the lower elevations mainly dry on Saturday and Sunday.
MORE Unsettled WEATHER AND SOMEWHAT COOLER WEATHER WILL RETURN
EARLY NEXT WEEK.

&&

.RIW Watches/Warnings/Advisories...None.

&&

$$

SHORT TERM...Lipson
LONG TERM...Skrbac
AVIATION...AR
FIRE WEATHER...Lipson




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