Overview of the Colorado Basin River Forecast Center Lisa Holts

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

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

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

NWS NOAA Mountain Mapper – Daily QC

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

Grids format

MAP

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

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

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

Processing IFP Data Table

Processing IFP Runtime Modifications

Processing IFP Unit Hydrograph Modification

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

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

Data sparse in Northern Arizona

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

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

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

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 ” Peaks Faster & Higher 2.00”1.00” Forecast For 24 Hours Flood Stage

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

NWSRFS-Three Components

Poorly Calibrated Basin Simulated Observed

Much Better Calibrated Basin

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

Interactive Forecast Program

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)

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

-> Future Time Today’s Conditions River / Res. Levels Soil Moisture Snowpack Future Streamflow Past <- Ensemble StreamFlow Prediction PrecipitationTemperature Start with Today’s Conditions - Create several possible future streamflow patterns - Based on historical climate.

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

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

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

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

Questions?