Overview of theColorado 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 Daily River Forecasts and Flood Forecastsand Flood Forecasts

Collect and QC data Collect and QC data Run Hydrologic ModelRun Hydrologic Model Produce daily river forecastsProduce daily river forecasts Manual forecast updates at Manual forecast updates at

– 6:30am, 11:00am, 4:00pm6:30am, 11:00am, 4:00pm

Automated forecast updates atAutomated forecast updates at– 12:00 am12:00 am

During floods… updates as needed/requestedDuring floods… updates as needed/requested

HydrologicModeling

Radar Data

River Gage Data

SnowPrecipitationForecasts

Soil Moisture StatesDeterministic / Probabilistic River Forecasts

ReservoirReleasesPrecipitation

Estimates

Satellite Data

Hydrologic Forecasting Hydrologic Forecasting Inputs/OutputsInputs/Outputs

TemperatureForecasts

NWS

NOAA

Mountain Mapper – Daily QC

Precipitation InputPrecipitation Input Multisensor Precipitation Estimates – MPEMultisensor Precipitation Estimates – MPE

– GageGage– RadarRadar– SatelliteSatellite

GridsGrids formatformat

MAPMAP

Future Precipitation & Temperature & Freezing Level

Point Values(HPC)

Grid Values(Prism Scaling)

Basin Values

5 days of QPF10 days temperatures

GFEGFE Increased leverage of GFEIncreased leverage of GFE

– View QPF differences View QPF differences between sourcesbetween sources

– Allows WFO to view QPF Allows WFO to view QPF going into the modelgoing into the model

Make adjustments in Make adjustments in specify stillspecify still

Future: will just use GFE Future: will just use GFE and eliminate specifyand eliminate specify

Example Display From NWSRFS-Interactive Forecast Program

Simulated -*

Observed - O

Adjusted=Forecast

ProcessingProcessingIFP Data TableIFP Data Table

ProcessingIFP Runtime Modifications

ProcessingIFP Unit Hydrograph Modification

Example:Hydrograph PlotCBRFC Web Site

NWSRFS Segments 500River Forecast Points 165

Forecast LimitationsForecast LimitationsQuality of forecast depends on inputsQuality of forecast depends on inputs

Observed precipitation

Observed flow

NWSRFSModel

Future Temperature

QPF

Data availability and Future uncertaintyModel states

Data sparse in Northern ArizonaData 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

1.00 0.50”

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

3.00 2.00”

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

2.00 1.00”

Peaks Faster & Higher

2.00” 1.00”

Forecast For 24 Hours

Flood Stage

NWS River Forecasting SystemNWS River Forecasting SystemNWSRFSNWSRFS

Collection of models and processesCollection of models and processes Three componentsThree components

– Calibration SystemCalibration System– Operational Forecasting SystemOperational Forecasting System– Ensemble Streamflow PredictionEnsemble Streamflow Prediction

NWSRFS-Three Components

Poorly Calibrated Basin

Simulated Observed

Simulated Observed

Much Better Calibrated Basin

Operational Forecast System Operational Forecast System (OFS)(OFS)

Preprocesses observed and future dataPreprocesses observed and future data Updates model state parametersUpdates model state parameters Provides short-term river and flood forecasts Provides short-term river and flood forecasts

– 0 to 14 days out– 0 to 14 days out

Interactive Forecast ProgramInteractive Forecast Program

Ensemble Streamflow Ensemble Streamflow Prediction (ESP)Prediction (ESP)

Uses historical precipitation, temperature Uses historical precipitation, temperature and evaporation dataand evaporation data

Uses current model statesUses current model states Produces mid- to long-range probabilistic Produces mid- to long-range probabilistic

forecast (weeks to months into the future)forecast (weeks to months into the future)

Ensemble Streamflow PredictionEnsemble Streamflow Prediction

ClimateForecast

Adjustments

Daily RFCForecasting•Data Ingest•Data QC•Model Updating

Current Conditions•Soil•Reservoir Levels•Streamflow

HistoricalTime Series

All Years ofRecord

ForecastTime

Series

Mean ArealTime Series

PrecipitationTemperature

NWSRFSHydrologic

Models

Time S

tre

am

flo

w

April-July

-> Future Time

Today’s Conditions

River / Res. Levels

Soil Moisture

Snowpack

19711972197319741975

1971

Future Streamflow

Past <-

Ensemble StreamFlow Prediction

7172737475

PrecipitationTemperature

Start with Today’s Conditions - Create several possible future streamflow patterns - Based on historical climate.

Supporting the Flash Flood Supporting the Flash Flood ProgramProgram

NWSRFS – Lumped 6 hourly modelNWSRFS – Lumped 6 hourly model CBRFC has recalibrated Arizona segments CBRFC has recalibrated Arizona segments

to an hourly time stepto an hourly time step blurred line when RFC can or cannot blurred line when RFC can or cannot

model eventmodel event For flash floods, RFC provides tools to help For flash floods, RFC provides tools to help

WFO decide when to issue FFWsWFO decide when to issue FFWs– FFG, FFPIFFG, 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 OperationsWater Supply Operations

Volumetric forecast for the runoff seasonVolumetric forecast for the runoff season Essential to water managers (dam operations, Essential to water managers (dam operations,

water allocation, water planning, etc..)water allocation, water planning, etc..) Issues January through JulyIssues January through July forecasters devote first 4 days of the month to forecasters devote first 4 days of the month to

water supply forecastingwater supply forecasting 146 water supply forecast points146 water supply forecast points Spring is the busiest time for the RFC Spring is the busiest time for the RFC

Water SupplyWater Supply Monthly water supply Monthly water supply

forecasts generated for forecasts generated for seasonal volumes seasonal volumes during winter / spring during winter / spring seasonsseasons

Questions?Questions?