FORECASTING EASTERN US WINTER STORMS Are We Getting Better and Why?

1. FORECASTING EASTERN US WINTER STORMSAre We Getting Better and Why? Jeff S. Waldstreicher NOAA/NWS Eastern Region Scientific Services Division – Bohemia, NY Northeast Regional Operational Workshop (NROW) November 4, 2004

2. OUTLINE • Winter Storm Warning Program • Verification Review • Key Activities and Developments • Relationship Between Event Totals and Warning Performance • Summary

3. MOTIVATION • Winter of 2003-2004 Performance • EASTERN REGION WIDE • POD - .921 • FAR - .321 • Lead Time – 18.5 hours • NORTHEAST • POD - .920 • FAR - .321 • Lead Time – 20.3 hours • Is this indicative of a positive performance trend? • If yes, what are the contributing factors?

6. WINTER STORM WARNINGVERIFICATION RESULTS 1993-94 to 2003-04

11. NORTHEASTPOD

12. NORTHEASTFAR

13. NORTHEASTLEAD TIME

14. KEY ACTIVITIES AND DEVELOPMENTS RELATED TO FORECASTING WINTER STORMS 1993-2004

15. NWP ADVANCES • Global Model • 1993 – AVN/MRF at T126/L28 • 2/day AVN to 126h and 1/day MRF to 240h • 2004 – GFS at T256/L64 to 84 h • 4/day to 384h (T170/L42 84-180h T126/L28 to 386h) • Numerous improvements to physics, data assimilation etc… • Medium Range Ensemble Forecast System (MREF) • ~1997 – 1/day 12 member system • 2004 – 4/day 48 member system including lag members • NGM– Static Since 1993

16. NWP ADVANCES • Eta (NAM) • 1993 – Early Eta 80 km / 38 levels / 00 and 12Z / 48h • 1995 – Meso Eta 32 km / 50 levels / 03 and 15Z / 33h • 2004 – MesoEta 12 km / 60 levels / 4 x day / 84 hr • Numerous improvements to physics, data assimilation etc… • Local Area Modeling - Workstation Eta • Short Range Ensemble Forecast System (SREF) • ~1999 – 10 members (5 48 km Eta / 5 RSM) • 2004 – 15 members (10- 32 km Eta / 5- 40 km RSM) • Rapid Update Cycle (RUC) • ~1994 – RUC1 – 60 km / 25 levels • 1998 – RUC2 – 40 km / 40 levels • 2004 – RUC2 – 20 km / 50 levels

17. 1994-1997 • WSR-88D Network Installation Completed • PCGRIDDS/NAWIPS/GARP • Gridded Model Data into Field Offices • NWS Lake Effect Snow Study • BUFKIT • Expansions of Snow Spotter Networks • Expansion of Collaborative Research Projects (COMET) • First Real-time local model in NWS ER field office (MM5 at BUF and BGM)

18. 1998-2000 • AWIPS Installations Completed • Advanced Workstations w/ Integrated Data Sets • Public Forecast Program Transfers • 1998-99 – BGM/CTP start Winter Warning Program • 1999-00 – AKQ/BTV/CAR/RNK start Winter Warning Program • Pros – New ideas/techniques, Smaller Forecast Areas • Cons – Less experience • Active Teletraining Program Established • Web based training modules

19. 1998-2000 • Regional Workshops/Conferences • Northeast Regional Operational Workshop • Southern New England Workshop • Great Lakes Operational Meteorology Workshop • Northeast Storm Conference • Continued Expansion of COMET Projects • CSTAR Collaborative Research Projects Funded • North Carolina State Univ. – WFO Raleigh (early 2000) • State Univ. of New York at Albany – WFO Albany (late 2000)

20. 2001-2004 • Eastern Region Winter Weather Best Practices Team (2001) • IFPS • Collaborative Forecast Process • HPC Winter Weather Experiment (WWE) • 2001-02 – 4 WFOs (AKQ/LWX/PHI/CTP) • 2002-03 – All Eastern Region • 2003-04 – ~75% of CONUS • 2004-05 – Integrated into routine HPC Operations • Test new collaborative forecast process among HPC and WFOs for winter storm events • Evaluate new products from SREF

21. 2001-2004 • Implementation of CSTAR Research Results • U. at Albany Project • Mesoscale Banding in Winter Storms • Precipitation Microphysics • Cold Season Closed Lows • Terrain-Forced Snow Storms • Impacts of Climate Regimes (ENSO, NAO, etc…) • N.C. State Project • Cold Air Damming • Coastal Fronts • Precipitation Type Forecasting Methodologies • Regional COMET Projects • BTV/McGill Univ. • OKX/Stony Brook Univ.

22. 2001-2004 • Weather Event Simulator (WES) – 2001 • Training Workstation that can simulate real-time data flow and forecast processes • AWIPS Archive Server- 2002 • Local Capability to archive full AWIPS data sets for WES playback • Expansion of local office training activities and workshops

23. 2001-2004 • Coming together of several activities and developments: • Applied Research and Technique Development • Technologies • Training • Operational Application and Procedures

24. Mesoscale Band Project Timeline

25. RELATIONSHIP BETWEEN EVENT COUNTS AND WARNING PERFORMANCE IMPACTS OF CLIMATE REGIMES?

26. ACTIVE SEASONS IN NORTHEAST>1200 Events

27. MODERATE SEASONS IN NORTHEAST800-1200 Events

28. LAMESEASONS IN NORTHEAST<800 Events

29. MONTHLY NAO/PNA vs. Events • Cumulative Winter (Dec-Jan-Feb-Mar) Monthly Mean NAO shows some correlation to number of winter storm events • Cumulative Winter Monthly Mean PNA shows little or no correlation • Shorter term (daily/weekly) index values likely more important

30. SUMMARY • Winter storm warning performance appears to be improving across the Northeast • Greatest improvements in Lead Time • Lead Time improvements are not a result of improved POD • No increase in false alarms noted • Event totals impact warning performance • More events – better performance • Most impact on False Alarms and Lead Time

31. SUMMARY Performance improvements appear to be related to an evolving “end-to-end” collaborative process of: • Discovery and Sharing • Demonstration of Added Value (Operational Utility) • Operational Implementation • Training Activities • Periodic Review and Refinement