Integration of Multiple Precipitation Estimates for Flash Flood Forecasting

1. Integration of Multiple Precipitation Estimates for Flash Flood Forecasting Reggina Cabrera NOAA/National Weather Service

2. Multisensor Precipitation Estimates (MPE) and Flash Flood Monitoring and Prediction (FFMP) Data sources Generation and usage of MPE and FFMP Limitations Work in progress In this presentation

3. TOOL that would provide a GOOD estimate of precipitation to improve lead-time for Flash Flood warning Ideal for Flash Flood Warning

4. National Weather Service Structure for Issuing Flash Flood Warning River Forecast Centers (RFC) Issues Flash Flood Guidance (FFG). Amount of rainfall needed in a given period to initiate flooding in small streams. Weather Forecast Office (WFO) Uses FFG to issue Flash Flood Warnings.

5. MPE and FFMP • MPE is used to feed Hydrologic models and create Flash Flood Guidance (FFG) • FFMP is fed with the FFG and used to issue Flash Flood warnings

6. MPE Allows evaluation of precipitation estimates from individual sensors as well as combined fields. It can be used also to fill areas with missing data. and… it is usedin real-time

7. FFMP Allows continuous monitoring of rainfall rate and accumulation with comparison to flash flood guidance for high resolution small basins and… it is also usedin real-time

8. Current Data Sources for MPE • Rain Gauges can provide good point value representations of precipitation at a small area at the surface. • Radar is excellent for delineating intensity and spatial distribution of precipitation. Represents precipitation above the ground. • Satellite provides nearly continuous geographical coverage but high cirrus often obscures details of precipitation.

9. Multi-scale requirements • MPE at the River Forecast Center can display only hourly multi-sensor estimates at a 4x4 Km • FFMP at the Weather Forecast Office can display the rainfall rate at every volume scan and rainfall accumulations for pre-defined small basins.

10. Satellite Data for Precipitation Estimates MPE can only display the hourly Hydro-Estimator products from NESDIS Local bias correction using gauge data is being evaluated

11. 0.45 in 0.67 in Satellite Estimates of Precipitation

12. Radar Data for Precipitation Estimates • MPE at the River Forecast Center can display only hourly multi-sensor estimates. • FFMP at the Weather Forecast Office can display the rainfall rate at every volume scan and accumulations • Radar bias corrections using gauge data is available

13. Comparison of MPE for Radar and Satellite

14. MPE and Radar Radar Coverage and Umbrellas in the Southeast USA Limitations of radar precipitation estimates: • Bright band and Hail contamination • Inaccurate Z/R relationship

15. RFC generates FFG1-, 3-, and 6-hour in HRAP ZCZC ATLFFGFFC CES FOUS62 KALR 060115 COUNTY FLASH FLOOD GUIDANCE...ATLANTA CWA NATIONAL WEATHER SERVICE SOUTHEAST RIVER FORECAST CENTER...ATLANTA GA 815 PM EST SUN MAR 5 2006 INCHES OF RAINFALL FOR SPECIFIED DURATIONS REQUIRED TO PRODUCE FLASH FLOODING IN FORECAST ZONES. LOWER AMOUNTS MAY CAUSE FLASH FLOODING IN URBAN OR MOUNTAINOUS AREAS. .B ATR 20060306 Z DH00/DC200603060115 /DUE/PPHCF/PPTCF/PPQCF :IDENTIFIERS ARE 2-LETTER STATE, Z FOR ZONE, 3-DIGIT ZONE NUMB : :IDENT 1HR 3HR 6HR ZONE NAME :======= ==== ==== ==== ==================== GAZ004 2.0/ 2.6/ 3.3 :WHITFIELD GAZ005 2.0/ 2.5/ 3.1 :MURRAY GAZ007 2.2/ 2.5/ 3.1 :GILMER GAZ011 1.8/ 2.2/ 2.6 :CHATTOOGA .END $$

16. ZCZC ATLFFGFFC CESFOUS62 KALR 060115COUNTY FLASH FLOOD GUIDANCE...ATLANTA CWA NATIONAL WEATHER SERVICE SOUTHEAST RIVER FORECAST CENTER...ATLANTA GA 815 PM EST SUN MAR 5 2006INCHES OF RAINFALL FOR SPECIFIED DURATIONS REQUIRED TO PRODUCEFLASH FLOODING IN FORECAST ZONES. LOWER AMOUNTS MAY CAUSE FLASH FLOODING IN URBAN OR MOUNTAINOUS AREAS. .B ATR 20060306 Z DH00/DC200603060115 /DUE/PPHCF/PPTCF/PPQCF :IDENTIFIERS ARE 2-LETTER STATE, Z FOR ZONE, 3-DIGIT ZONE NUMB: :IDENT 1HR 3HR 6HR ZONE NAME :======= ==== ==== ==== ==================== GAZ031 2.3/ 2.7/ 2.9 :PAULDINGGAZ032 2.2/ 2.5/ 2.7 :COBBGAZ033 2.1/ 2.4/ 2.6 :FULTON-NORTHGAZ034 2.5/ 2.9/ 3.1 :GWINNETTGAZ112 2.5/ 3.1/ 3.5 :MONTGOMERYGAZ113 2.6/ 3.2/ 3.5 :TOOMBS.END$$ In the past…

17. Now….FFMP B ATR 20060306 Z DH00/DC200603060115 /DUE/PPHCF/PPTCF/PPQCF :IDENTIFIERS ARE 2-LETTER STATE, Z FOR ZONE, 3-DIGIT ZONE NUMB: :IDENT 1HR 3HR 6HR ZONE NAME :======= ==== ==== ==== ==================== GAZ031 2.3/ 2.7/ 2.9 :PAULDINGGAZ032 2.2/ 2.5/ 2.7 :COBBGAZ033 2.1/ 2.4/ 2.6 :FULTON-NORTHGAZ034 2.5/ 2.9/ 3.1 :GWINNETTGAZ112 2.5/ 3.1/ 3.5 :MONTGOMERYGAZ113 2.6/ 3.2/ 3.5 :TOOMBS.END

18. Use other tools with FFMP • Looping Radar Images • MPE • Satellite estimates • Lightning Modifying FFG Urbanization Deforestation Fire Scars

19. FFMP Output Map and Table of: Basin rainfall accumulation Ratio of basin accumulations to FFG Difference between accumulations and FFG For time periods from 30 minutes to 6 hours Line graph of basin rainfall, basin rainfall rate, and FFG for the same time periods

21. FFMP Limitations • Radar estimates of rainfall accumulations may be inaccurate. • FFMP displays may mask problems. • Flash Flood Guidance is not always representative of basins. • Does not account for rainfall since data cutoff • Does not always represent special cases… urban centers, deforestation, fire scars.

22. Improvements for Flash Flood Warning Precipitation on the ground… QPE Forecast Precipitation….. QPF FFG generated at a smaller resolution

23. NOWCAST of precipitation Extrapolation of radar rates field forward in time using local pattern matching technique

24. Gridded FFG at smaller resolution???

25. Questions ?

26. RADAR COVERAGE MAP PRECIPITATION MOSAIC

28. 164 DOPPLER RADARS -good spatial and temporal coverage -problems in mountains 3 GEOSTATIONARY SATELLITES -could provide 15 minute 1 km imagery -cloud top temperatures based precipitation estimation algorithms 991 NWS ASOS STATIONS WITH HEATED TIPPING BUCKETS -good for point value estimates of precipitation OTHER SOURCES OF AUTOMATED GAGE OBS -timeliness and data quality problems.