1. Overview of the Colorado Basin River Forecast Center Lisa Holts

2. What we do…. Support Flash Flood Program Event Driven (rain, snowmelt) River Forecasts Recreational Forecasts (River trends – Peak Flows) Water Supply => Reservoir Management Colorado Basin River Forecast Center Our Mission: Protection of lives and property – Enhancement of the nation’s economy WFO and RFC partnership

3. Daily River Forecasts and Flood Forecasts  Collect and QC data  Run Hydrologic Model  Produce daily river forecasts  Manual forecast updates at –6:30am, 11:00am, 4:00pm  Automated forecast updates at –12:00 am  During floods… updates as needed/requested

4. Radar Data River Gage Data Snow Precipitation Forecasts Soil Moisture States Deterministic / Probabilistic River Forecasts Reservoir Releases Precipitation Estimates Satellite Data Hydrologic Forecasting Inputs/Outputs Temperature Forecasts

5. NWS NOAA Mountain Mapper – Daily QC

6. Precipitation Input  Multisensor Precipitation Estimates – MPE –Gage –Radar –Satellite

7. Grids format

8. MAP

9. Future Precipitation & Temperature & Freezing Level Point Values (HPC) Grid Values (Prism Scaling) Basin Values 5 days of QPF 10 days temperatures

10. GFE  Increased leverage of GFE –View QPF differences between sources –Allows WFO to view QPF going into the model  Make adjustments in specify still  Future: will just use GFE and eliminate specify

11. Example Display From NWSRFS- Interactive Forecast Program Simulated -* Observed - O Adjusted=Forecast

12. Processing IFP Data Table

13. Processing IFP Runtime Modifications

14. Processing IFP Unit Hydrograph Modification

15. Example: Hydrograph Plot CBRFC Web Site NWSRFS Segments 500 River Forecast Points 165

16. Forecast Limitations Quality of forecast depends on inputs Observed precipitation Observed flow NWSRFS Model Future Temperature QPF Data availability and Future uncertainty Model states

17. Data sparse in Northern Arizona

18. Forecast Limitations Colorado Basin River Forecast Center Future Uncertainty - Precipitation Amounts & Timing Are Perfect: BUT Wrong Basin 2.00”1.00” Result No Rise 2.00”1.00” Forecast Flood Stage

19. Forecast Limitations Colorado Basin River Forecast Center Future Uncertainty - Precipitation Basin Is Right: BUT Forecast Amounts Too High Result 1.000.50” Peaks Lower Forecast 2.00”1.00” Flood Stage

20. NWS NOAA Forecast Limitations Colorado Basin River Forecast Center Future Uncertainty - Precipitation Basin Is Right: BUT Forecast Amounts Too Low Result 3.002.00” Peaks Higher 2.00”1.00” Forecast Flood Stage

21. NWS NOAA Forecast Limitations Colorado Basin River Forecast Center Future Uncertainty - Precipitation Basin Is Right-Amounts are Right: wrong intensity Result: Packed Into 6 hours 2.001.00” Peaks Faster & Higher 2.00”1.00” Forecast For 24 Hours Flood Stage

22. NWS River Forecasting System NWSRFS  Collection of models and processes  Three components –Calibration System –Operational Forecasting System –Ensemble Streamflow Prediction

23. NWSRFS-Three Components

24. Poorly Calibrated Basin Simulated Observed

25. Much Better Calibrated Basin

26. Operational Forecast System (OFS)  Preprocesses observed and future data  Updates model state parameters  Provides short-term river and flood forecasts – 0 to 14 days out

27. Interactive Forecast Program

28. Ensemble Streamflow Prediction (ESP) Ensemble Streamflow Prediction (ESP)  Uses historical precipitation, temperature and evaporation data  Uses current model states  Produces mid- to long-range probabilistic forecast (weeks to months into the future)

29. Ensemble Streamflow Prediction Climate Forecast Adjustments Daily RFC Forecasting Data Ingest Data QC Model Updating Current Conditions Soil Reservoir Levels Streamflow Historical Time Series All Years of Record Forecast Time Series Mean Areal Time Series Precipitation Temperature NWSRFS Hydrologic Models Time Streamflow April-July

30. -> Future Time Today’s Conditions River / Res. Levels Soil Moisture Snowpack 1971 1972 1973 1974 1975 1971 Future Streamflow Past <- Ensemble StreamFlow Prediction 71 72 73 74 75 PrecipitationTemperature Start with Today’s Conditions - Create several possible future streamflow patterns - Based on historical climate.

32. Supporting the Flash Flood Program  NWSRFS – Lumped 6 hourly model  CBRFC has recalibrated Arizona segments to an hourly time step  blurred line when RFC can or cannot model event  For flash floods, RFC provides tools to help WFO decide when to issue FFWs –FFG, FFPI

33. Soil type ? Vegetation type and density ? Land Use ? Fire activity ? Slopes? Try to qualify the flash flood threat Highlight flash flood prone areas Flash Flood Potential Index concept

34. Water Supply Operations  Volumetric forecast for the runoff season  Essential to water managers (dam operations, water allocation, water planning, etc..)  Issues January through July  forecasters devote first 4 days of the month to water supply forecasting  146 water supply forecast points  Spring is the busiest time for the RFC

35. Water Supply  Monthly water supply forecasts generated for seasonal volumes during winter / spring seasons

36. Questions?