Jess CharbaJess CharbaFred SamplatskyFred Samplatsky

Meteorological Development LaboratoryMeteorological Development LaboratoryNational Weather Service, NOAANational 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/

Comparative Verification of Comparative Verification of Experimental HR QPFs with Model and Experimental HR QPFs with Model and Forecaster-Prepared QPFs in the NWSForecaster-Prepared QPFs in the NWS

What is HR QPF ?What is HR QPF ? HR QPF = HR QPF = hhigh spatial and intensity igh spatial and intensity rresolution esolution

qquant. uant. pprecip forecastsrecip forecasts• GFS-based MOS experimental modelGFS-based MOS experimental model

• Produced 2x / day since June 2008Produced 2x / day since June 2008

• On 4-km grid over CONUSOn 4-km grid over CONUS

• Two articles in Jan 2011 issue of MWRTwo articles in Jan 2011 issue of MWR

HR QPF elementsHR QPF elements• QPF = “single value” precip amountQPF = “single value” precip amount

• PQPF = probabilities for precip thresholdsPQPF = probabilities for precip thresholds

• PoP = probability of precipPoP = probability of precip

• 6- and 12-h valid periods6- and 12-h valid periods

• 6-h projections to “day” 6.5 (day 8 for PoP) 6-h projections to “day” 6.5 (day 8 for PoP)

ObjectiveObjective

Use comparative scoring to see whether Use comparative scoring to see whether HR QPF elements provideHR QPF elements provide• Better model guidance than presently Better model guidance than presently

availableavailable

Compare HR performance with Compare HR performance with forecasters atforecasters at• HPC (NCEP Hydromet. Predict. Center)HPC (NCEP Hydromet. Predict. Center)• WFOs (produce NDFD QPFs)WFOs (produce NDFD QPFs)

Compare HR performance with MOSCompare HR performance with MOS

Model QPF Guidance Included Model QPF Guidance Included in Verificationin Verification

NCEP modelsNCEP models• NAMNAM• GFSGFS• HPC 6-h PQPF “hybrid” exp. model HPC 6-h PQPF “hybrid” exp. model

fits prob. density function to ensemble model and HPC fits prob. density function to ensemble model and HPC forecaster QPFsforecaster QPFs

Gridded MOS QPF and PoPGridded MOS QPF and PoP

MOS QPF (at MOS stations)MOS QPF (at MOS stations)

Human-Prepared Grids Human-Prepared Grids Included In VerificationIncluded In Verification

HPC 6-h QPFHPC 6-h QPF

NDFD NDFD (Nat. Digit. Fcst. Database prod. by WFOs)(Nat. Digit. Fcst. Database prod. by WFOs)

• 6-h QPF6-h QPF

• 12-h PoP12-h PoP

QPF Issuance Times (1200 Z Cycle)QPF Issuance Times (1200 Z Cycle)

Model cut-off timeModel cut-off time• ~ 1800 Z~ 1800 Z

Human cut-off timeHuman cut-off time• HPC ~ 2200 ZHPC ~ 2200 Z• NDFD ~ 0000 Z (next day)NDFD ~ 0000 Z (next day)

Verification Data and ScoringVerification Data and Scoring

Stage IV quantitative precip estimates Stage IV quantitative precip estimates (QPE) (QPE)

Scoring performed on 4-km QPE grid and Scoring performed on 4-km QPE grid and at MOS stationsat MOS stations

Independent verification samplesIndependent verification samples• Period = Oct 2009 – Nov 2010Period = Oct 2009 – Nov 2010

• Cool (Oct – Mar) and warm (Apr – Sep) seasonsCool (Oct – Mar) and warm (Apr – Sep) seasons

CONUS domainCONUS domain

6-h Cat. QPF6-h Cat. QPF

4-km grid4-km gridCool seasonDay 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

Models only

Cool seasonDay 3

Oct 2009 – Mar 2010

6-h Cat. QPF6-h Cat. QPF

1647 MOS stations1647 MOS stations

Notes Similar rankings -

Warm season

Thru Day 6.5

Cool seasonDay 3

Models GMOS, HR

Humans NDFD

Cool season

Oct 2009 – Mar 2010

12-h PoP12-h PoP

4-km grid4-km grid

BSS = Brier skill score BSS = Brier skill score

Note Similar rankings for -

Warm season

6-h PQPF 6-h PQPF

4-km grid4-km gridWarm seasonDay 1

Models only

Apr ’10 – Sep ’10

Notes Similar ranking -

Cool season

Days 2 and 3

6-h PQPF6-h PQPF

Reliability Reliability

4-km grid4-km grid

Warm seasonDay 1

Models only

Apr ’10 – Sep ’10

Notes Similar results -

Cool season

Days 2 and 3

6-h PQPF6-h PQPF

Reliability Reliability

4-km grid4-km grid

Warm seasonDay 1

Models only

Apr ’10 – Sep ’10

Notes Similar results -

Cool season

Days 2 and 3

6-h PQPF6-h PQPF

Sharpness Sharpness

4-km grid4-km grid

Warm seasonDay 1

Models only

Apr ’10 – Sep ’10

Notes Similar results -

Cool season

Days 2 and 3

For cat. QPF grids HR scored For cat. QPF grids HR scored

• Somewhat better than HPC and WFO Somewhat better than HPC and WFO

(NDFD) forecasters(NDFD) forecasters

• Much better than NCEP models and Much better than NCEP models and

GMOSGMOS

For cat. QPF at MOS stationsFor cat. QPF at MOS stations

• HR improved on MOS but less than for HR improved on MOS but less than for

GMOSGMOS

Findings SummaryFindings Summary

Findings Summary (cont.)Findings Summary (cont.)

For PoP grids HR skillFor PoP grids HR skill

• Better than GMOS and NDFDBetter than GMOS and NDFD

For PQPF model grids For PQPF model grids

• HR and HPC PQPFs have similar skillHR and HPC PQPFs have similar skill

• HR better reliab.; HPC better sharpness HR better reliab.; HPC better sharpness

HR and HPC PQPFs may complement each HR and HPC PQPFs may complement each

other other

HR Implementation PlansHR Implementation Plans

HR QPF and PoP grids will replace GMOS grids HR QPF and PoP grids will replace GMOS grids over CONUS in spring 2011over CONUS in spring 2011

Issuance of HR PQPF grids expected later in Issuance of HR PQPF grids expected later in 20112011

Questions ?Questions ?