Ensembles in CHPS (XEFS)

NEWS AND ACTIVITIES (in reverse chronological order)

October 2008

In August, OHD kicked off requirements gathering work for the Ensembles Product Generator (EPG), as defined in the XEFS Design & Gap Analysis report. The project leader is Hank Herr; his team includes representatives from OCWWS, OHD HSMB, CNRFC, CBRFC, and Deltares. Technical consultants will be added as needed. The team is in the process of defining product requirements for XEFS, and has begun by considering a range of products currently available in various RFC/regional web pages, reports, and presentations.

OHD hosted a visit in early September by Albrecht Weerts of Deltares; Albrecht is the Deltares focal point for ensembles in CHPS.

July 2008

HSMB now has access to a FEWS-based version of the XEFS prototype software.

The annual Hydrologic Ensemble Prediction Experiment (HEPEX) conference was held in Delft, Netherlands in June. Deltares continues to collaborate with the NWS on hydrologic ensembles.

Activities related to ensembles capabilities in CHPS are not scheduled to begin until CY 2009.

April 2008

Following Gary Carter’s approval of the CAT’s recommendation to proceed with FEWS as the software infrastructure for CHPS, planning activities to include an ensemble forecasting capability began in earnest. FEWS already contains the basic computational elements to generate a climatology-based ensemble; this feature was added to the CHPS pilot system in December 2007 and demonstrated at NCRFC. However, until the basic CHPS components are in place, work on the XEFS sub-system of CHPS must take a back seat for a while.

Meanwhile HSEB made good progress on porting HSMB HEP’s existing prototype software to the FEWS environment. Output from the classical climatology-based Ensemble Pre-Processor (EPP) and the Ensemble Post-Processor can now be successfully displayed via the FEWS time series viewer. HSEB hopes to provide HEP with a more complete version by early May as a first step towards transitioning the HSMB from its previous development environment to a more CHPS-compatible framework.

January 2008

On October 19 HSEB submitted a "High Level Analysis and Design" document to the XEFS Implementation Team for review. This document contained a proposed software design to meet the requirements specified in the XEFS Design and Gap Analysis Report (available at http://www.weather.gov/oh/rfcdev/docs/XEFS_design_gap_analysis_report_final.pdf).

In December HSEB held a meeting to address feedback received on the document. However the discussion prompted a re-think of the implementation strategy, which – until that point - had been to develop a solution based on CHPS concepts but independently of FEWS.

Since it was becoming clear that FEWS would be the solution of choice for CHPS the XEFS Execution Manager, in consultation with the XEFS Oversight Group and numerous other subject matter experts, determined that the XEFS software design should be based entirely on FEWS. This is the most cost effective and least risky path to take.

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October 2007

HSEB spent most of this quarter conducting an in-depth analysis of existing prototype software that is related to experimental hydrologic ensembles. That analysis, along with an examination of requirements captured in the XEFS Design and Gap Analysis Report (available at http://www.weather.gov/oh/rfcdev/docs/XEFS_design_gap_analysis_report_final.pdf), forms the basis of a high level software design for the XEFS. With the design in place, the XEFS Execution Manager is in the process of putting together a preliminary implementation plan, and specifying cross-functional team composition. An XEFS implementation kick-off meeting is expected in October.

The XEFS Execution Manager announced a one-month slip in the schedule, due to some AWIPS OB9 work which has impacted key XEFS resources.

July 2007

In May the XEFS Design and Gap Analysis Team, led by DJ Seo (HSMB) and Rob Hartman (CNRFC) presented to the Director of OHD, Gary Carter, a report entitled "The Experimental Ensemble Forecast System (XEFS) Design and Gap Analysis: Report of the XEFS Design and Gap Analysis Team", dated May 11, 2007. The report is available on the web at: http://www.weather.gov/oh/rfcdev/docs/XEFS_design_gap_analysis_report_final.pdf. This report provides a summary of current prototype Ensembles functionality developed by HSMB, and an identification of functionality that will be required to introduce an initial (experimental) short-to-long term Ensembles capability into RFC operations. Incremental enhancements to the XEFS will ultimately result in a fully operational Hydrologic Ensemble Forecast System (HEFS).

Gary Carter accepted the findings in the report and subsequently tasked HSEB with formulating an execution plan. Chris Dietz (HSEB) has been assigned as the XEFS Execution Manager, supported by an Oversight Committee whose members include DJ Seo, Chris Dietz, Rob Hartman, and Mary Mullusky (OCWWS).

HSEB has now formed a 4-person software engineering team (the final member will arrive on July 9) and has begun an in-depth analysis of the prototype software. The software architect, Sudha Rangan, has begun the process of formulating a design consistent with CHPS. A draft implementation plan is expected by the end of August 2007.

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