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Jess Charba Fred Samplatsky Meteorological Development Laboratory

Comparative Verification of Experimental HR QPFs with Model and Forecaster-Prepared QPFs in the NWS. Jess Charba Fred Samplatsky Meteorological Development Laboratory National Weather Service, NOAA.

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Jess Charba Fred Samplatsky Meteorological Development Laboratory

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  1. Comparative Verification of Experimental HR QPFs with Model and Forecaster-Prepared QPFs in the NWS Jess Charba Fred Samplatsky Meteorological Development Laboratory National Weather Service, NOAA Details = http://ams.confex.com/data/manuscript/ams/91Annual/Paper_177686_manuscript_132_0.pdf HR QPF website = http://www.weather.gov/mdl/hrqpf/

  2. What is HR QPF ? • HR QPF = high spatial and intensity resolution quant. precip forecasts • GFS-based MOS experimental model • Produced 2x / day since June 2008 • On 4-km grid over CONUS • Two articles in Jan 2011 issue of MWR • HR QPF elements • QPF = “single value” precip amount • PQPF = probabilities for precip thresholds • PoP = probability of precip • 6- and 12-h valid periods • 6-h projections to “day” 6.5 (day 8 for PoP)

  3. Objective • Use comparative scoring to see whether HR QPF elements provide • Better model guidance than presently available • Compare HR performance with forecasters at • HPC (NCEP Hydromet. Predict. Center) • WFOs (produce NDFD QPFs) • Compare HR performance with MOS

  4. Model QPF Guidance Included in Verification • NCEP models • NAM • GFS • HPC 6-h PQPF “hybrid” exp. model • fits prob. density function to ensemble model and HPC forecaster QPFs • Gridded MOS QPF and PoP • MOS QPF (at MOS stations)

  5. Human-Prepared Grids Included In Verification • HPC 6-h QPF • NDFD (Nat. Digit. Fcst. Database prod. by WFOs) • 6-h QPF • 12-h PoP

  6. QPF Issuance Times (1200 Z Cycle) • Model cut-off time • ~ 1800 Z • Human cut-off time • HPC ~ 2200 Z • NDFD ~ 0000 Z (next day)

  7. Verification Data and Scoring • Stage IV quantitative precip estimates (QPE) • Scoring performed on 4-km QPE grid and at MOS stations • Independent verification samples • Period = Oct 2009 – Nov 2010 • Cool (Oct – Mar) and warm (Apr – Sep) seasons • CONUS domain

  8. 6-h Cat. QPF4-km grid Cool season Day 1 Models NAM, GFS, GMOS, HR Humans HPC, NDFD Oct 2009 – Mar 2010 Notes Similar rankings - Warm season Days 2 – 3 12-h valid period

  9. 6-h Cat. QPF1647 MOS stations Cool season Day 3 Cool season Day 3 Models only Oct 2009 – Mar 2010 Notes Similar rankings - Warm season Thru Day 6.5

  10. 12-h PoP4-km gridBSS = Brier skill score Cool season ModelsGMOS, HR Humans NDFD Oct 2009 – Mar 2010 Note Similar rankings for - Warm season

  11. 6-h PQPF 4-km grid Warm season Day 1 Models only Apr ’10 – Sep ’10 Notes Similar ranking - Cool season Days 2 and 3

  12. 6-h PQPFReliability 4-km grid Warm season Day 1 Models only Apr ’10 – Sep ’10 Notes Similar results - Cool season Days 2 and 3

  13. 6-h PQPFReliability 4-km grid Warm season Day 1 Models only Apr ’10 – Sep ’10 Notes Similar results - Cool season Days 2 and 3

  14. 6-h PQPFSharpness 4-km grid Warm season Day 1 Models only Apr ’10 – Sep ’10 Notes Similar results - Cool season Days 2 and 3

  15. Findings Summary • For cat. QPF grids HR scored • Somewhat better than HPC and WFO (NDFD) forecasters • Much better than NCEP models and GMOS • For cat. QPF at MOS stations • HR improved on MOS but less than for GMOS

  16. Findings Summary (cont.) • For PoP grids HR skill • Better than GMOS and NDFD • For PQPF model grids • HR and HPC PQPFs have similar skill • HR better reliab.; HPC better sharpness • HR and HPC PQPFs may complement each other

  17. HR Implementation Plans • HR QPF and PoP grids will replace GMOS grids over CONUS in spring 2011 • Issuance of HR PQPF grids expected later in 2011

  18. Questions ?

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