Overview of the Colorado Basin River Forecast Center

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

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

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

5. NOAA Mountain Mapper – Daily QC NWS

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

7. Gridsformat

8. MAP

9. Point Values (HPC) Basin Values Grid Values (Prism Scaling) Future Precipitation & Temperature & Freezing Level 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. ProcessingIFP 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 LimitationsQuality of forecast depends on inputs Observed precipitation Future Temperature QPF Observed flow NWSRFS Model Model states Data availability and Future uncertainty

17. Data sparse in Northern Arizona

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

19. Forecast Result 1.00 2.00” 0.50” 1.00” Flood Stage Peaks Lower Forecast Limitations Future Uncertainty - Precipitation Basin Is Right: BUT Forecast Amounts Too High Colorado Basin River Forecast Center

20. NOAA NWS Forecast Result 3.00 2.00” 2.00” 1.00” Flood Stage Peaks Higher Forecast Limitations Future Uncertainty - Precipitation Basin Is Right: BUT Forecast Amounts Too Low Colorado Basin River Forecast Center

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

22. NWS River Forecasting SystemNWSRFS • 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 Simulated Observed

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

30. 71 72 73 74 75 1971 1972 1973 1974 1975 Temperature Precipitation Ensemble StreamFlow Prediction Future Streamflow Today’s Conditions River / Res. Levels Soil Moisture Snowpack Past <- -> Future Time 1971 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. Land Use ? Soil type ? Vegetation type and density ? Fire activity ? Slopes? Flash Flood Potential Index concept Try to qualify the flash flood threat Highlight flash flood prone areas

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?