1. Hydrometeorological Prediction Center HPC Medium Range Grid Improvements Mike Schichtel, Chris Bailey, Keith Brill, and David Novak

2. Hydrometeorological Prediction Center Staffed 1030-1930 UTC by two forecasters -Temperatures/Pop Desk Max/MinT and PoP Grids -Pressure/Fronts Desk Winds Grids Medium Range Desk Preliminary grids issued by 1415 UTC (15 UTC deadline) -including 00 UTC ECMWF ensemble Final grids usually issued by 18 UTC (20 UTC deadline) -incorporating 12 UTC guidance suite without ECMWF Temps/PoP Pressure/Fronts Sky, Dewpoint, and Wx derived

3. Hydrometeorological Prediction Center HPCGuide Medium Range 5 km Grids DEWPOINTS CLOUD COVER WEATHER TYPE MIN TEMPS MAX TEMPS WINDS 12 HOUR POPS

4. Hydrometeorological Prediction Center Day 7 Skill 2008 = Day 5 Skill 2001! _ _ _ _ _ _ _ _

5. Hydrometeorological Prediction Center Anomaly correlation die-off scores of Model and Ensemble Mean Forecasts

6. Hydrometeorological Prediction Center Total: 288 individual runs per day! ModelCycle (UTC)Run Duration (Days) Members per Day ECMWF00, 12102 DGEX06, 1882 ECMWF Ens.00, 1210102 GFS00, 06, 12, 18164 GEM Global00, 12102 UKMET00, 1262 NOGAPS00, 06, 12, 1884 NAEFS00, 121640 FNMOC Ens.0010 GFS Ens.00, 06, 12, 181680 GEM Ens.00, 121640 Primary Medium Range Models/Ensembles at HPC

7. Hydrometeorological Prediction Center Full International Guidance Suite including ECMWF deterministic and ensemble and bias- corrected NAEFS Medium Range Data GEFS Member ECMWF Member CMC Member ECMWF Mean NAEFS Mean GEFS Mean GFS ECMWF 90 Ensemble members

8. Hydrometeorological Prediction Center Maximum Temps vs. GFS MOS HPC Continuity NDFD Continuity HPCICTDGEX GFSECMWFMSC ECMWF Ens Forecaster compares an international guidance suite, GFS MOS, climatology, and HPC and NDFD (NWS) continuity Forecaster chooses blends and weights Forecast Process Blender Final Product

9. Hydrometeorological Prediction Center Improvements Made Td and Sky April 15, 2010: Methods to derive Dew Point and Sky Changed. MAE improved up to 20%. Sky: Model guidance weighted according to forecaster’s PoP blends. No downscaling. Dew Point: Model guidance weighted according to forecaster’s Max/MinT blends. Downscaled by using a GDAS-RTMA difference accumulated by applying a decaying weight through time. Testing June 09 – Jan 2010 (green = new) Testing Feb 2010 (green = new) Better in Cool Season

10. Hydrometeorological Prediction Center Improvements Made Td Comparison Before MDL Verification Comparison of April-Sept (00 UTC cycle) HPC (green) highest medium range MAE

11. Hydrometeorological Prediction Center Improvements Made Td Comparison After Change MDL Verification Comparison April-Sept (00 UTC cycle) HPC (green) now lowest MAE Given longer history verification shown in slide #9, HPC skill should be better during cool season

12. Hydrometeorological Prediction Center Latest Improvements Operational as of November 2: Increased use of model guidance downscaled using RTMA instead of PRISM. New Day 7 skill equals = Old method Day 5.5 _ _ _ _ This new HPC DS_FNL score does not yet reflect additional benefits from bias corrections and forecaster modifications

13. Hydrometeorological Prediction Center New Day 7 skill equals = Old method Day 5.5 _ _ _ _ _ _ _ _ _ This new HPC DS_FNL score does not yet reflect additional benefits from bias corrections and forecaster modifications

14. Hydrometeorological Prediction Center Other Elements Wind Speed Jul ‘09 – Jul ‘10 HPC similar to NDFD

15. Hydrometeorological Prediction Center Other Elements 12 h PoP Jul ‘09 – Jul ‘10 HPC better than MOS and similar to NDFD

16. Hydrometeorological Prediction Center Improvements Prototyped 6 h Floating Pop Real-time prototyped images available at: http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody_newparms.html http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody_newparms.html Which can be compared to the operational suite at: http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html 6 h statistical PoPs generated from international model suite The 6 h period with the higher PoP is set to the HPC 12 h PoP (consistent with floating PoP principles) The remaining 6 h period is assigned the statistical 6 h PoP value Renamed “Precipitation Likelihood Index” to avoid public confusion.

17. Hydrometeorological Prediction Center Improvements Prototyped Weather Grid Enhancements Real-time prototyped images available at: http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody_newparms.html http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody_newparms.html Which can be compared to the operational suite at: http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html Time resolution increased from 12 h to 6 hourly Precipitation Type Algorithm improved (top-down approach) Slight chance, chance, and likely qualifiers added (based on HPC PoP)

18. Hydrometeorological Prediction CenterCollaboration Academia / Publications Conferences (like NROW) CSTAR »Rossby Wave Packets etc. EMC / THORPEX -Adaptive Observations »Targeting Observation Program WFOs/RFCs -12Planet Chatroom and coordination calls

19. Hydrometeorological Prediction Center HPC uses full suite of international model guidance Given limited forecaster resources, increasingly relying on forecaster blending input coupled with post processing Improvements to Td and Sky have been made Improvements to PoP and Wx grids prototyped Improvements to Max/MinTemps November 2010 (now!) Open to suggestions for improvement Summary