NWSRFS Ensemble Streamflow Prediction

1. NWSRFSEnsemble Streamflow Prediction Gerald (Jay) Day 2290 East Prospect Road, Suite 1 Fort Collins, Colorado 80525

2. Ensemble Probabilistic Forecasting • Hydrologic simulation using historic precipitation and temperature • Frequency analysis using “conditioned” hydrologic time series traces

3. ESP Forecast Applications • Water Supply Forecasts • Spring Flood Outlooks • Drought Analysis • Hydropower Planning • Fisheries Management • Recreation • Navigation • Reservoir Inflow Forecasts

4. Hydropower • Water Supply • Recreation • Flood Control • Hydropower • Navigation • Water Quality • Fisheries • Recreation Water Management Considerations

5. Soil Moisture in the Lake Lanier Basin

6. Lake Lanier Inflow Forecast – June 1988

7. NWSRFS Structure Operational Forecast System Hydrologic Operations Ensemble Streamflow Prediction System Calibration System

8. NWSRFS Software Overview OPERATIONAL FORECAST SYSTEM ENSEMBLE STREAMFLOW PREDICTION SYSTEM Automatic Data Entry Functions Forecast Functions Preprocessor Functions Processed Data Files Observed Data Files ESP Functions Forecast Parameter and Carryover Files ESP Time Series Files Pre-Processor Parameter Files Manual Preparation ESP Parameter Files ESP Initialization Program CALIBRATION SYSTEM Manual Calibration Program Historical Data Access Programs Historical Data Parametric Data Calibration Data Files Calibration Pre-processors and Calibration Utility Automatic Parameter Optimizer

9. POSITIONAL CLIMATOLOGICAL INFORMATION ESP Procedure CURRENT CONDITIONS • SOIL MOISTURE • SNOW PACK PRESENT • RESERVOIR LEVELS • STREAMFLOW HISTORICAL TIME SERIES ALL YEARS OF MEAN AREAL RECORD NWSRFS TIME SERIES STREAMFLOW HYDROLOGIC PRECIPITATION MODELS TEMPERATURE FORECAST TIME SERIES TIME FORECASTS AND OUTLOOKS STATISTICAL • WATER SUPPLY ANALYSIS • OTHER WATER MGMT INFORMATION WINDOW

10. ESP Analysis and Display Program (ESPADP)

11. ESPADP Trace Ensemble Plot

12. ESPADP Expected Value Plot

13. ESPADP Probability Histogram

14. ESPADP Exceedance Probability Plot

16. ESPADP Analysis Variables Number of days above flood stage Instantaneous Peak Flow Mean Daily Peak Volume of flow Number of days until flood stage is exceeded Flow Flood stage Minimum instantaneous flow Time

17. ESP Computed Variables • Variables that can be calculated for specified window: • Maximum mean daily value and number of days to maximum mean daily value • Minimum mean daily value and number of days to minimum mean daily value • Mean daily value • Volume • Maximum instantaneous value and number of days to maximum instantaneous value • Minimum instantaneous value and number of days to minimum instantaneous value • Number of days until time series gets above (or below) a specified criterion • Number of days time series remains above (or below) a specified criterion

18. ESPADP Observed and Conditional Simulation

19. ESPADP Observed and Historical Simulation

20. Meteorological Forecast Information • 1 to 5 Day Forecasts • 6 to 10 Day Categorical Forecasts • Monthly / Seasonal Outlooks

21. 1 –5 Day Forecasts Temperature Precipitation

22. 6 – 10 Day Forecasts Temperature Precipitation

23. Seasonal Outlook Temperature Precipitation

24. ESPADP Pre-adjustment Technique

25. ESPADP Year Weighting • Used to incorporate Climate Forecast Information • Post ESP analysis procedure • Weights are set based on the similarity of a historical year to the current year • Can be used to exclude historical years

26. ESP Example