Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for the 2005 Water Year

1. Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for the 2005 Water Year Steve King, Hydrologist Northwest River Forecast Center

2. Topics for Presentation • Northwest River Forecast Center: • Overview • NWRFC Forecasting Models and Products • NWS River Forecast System • Statistical Water Supply Forecasts • Use of ESP to Produce Longterm Forecasts • 2005 Volumetric Outlook • Incorporation of Climate Forecasts into ESP

3. Mission of NWRFC • National Weather Service mission: • Provide weather, hydrologic, and climate forecasts and warnings... • ...for the protection of life and property... • ...and the enhancement of the national economy. • The NWRFC accomplishes the NWS mission by: • Providing unbiased hydrologic information to a wide • variety of users including: Short, Medium and Long Range River Forecasts Water Supply Volume Forecasts Unregulated Streamflow Estimates

4. NWS River Forecast Centers

5. Northwest River Forecast Center Columbia Basin Coastal Drainages of Oregon and Washington 6 States & CANADA 9 NWS Field Offices (WFOs) Total Area: 315,795 Grand Coulee Dam Lower Granite Dam The Dalles Dam The Willamette at Salem

6. Hydrologic Forecasting:Time Domains Flow Time

7. NWRFC Forecasting Models • NWS River Forecast System • Short, Medium, and Longterm capabilities • Lumped, Conceptual, Continuous • Run in deterministic AND ensemble (ESP) mode • Statistical Water Supply & Peak Flow Model • Seasonal Forecasts • Regression techniques

8. Northwest RFC • Forecast Services • NWS Flood Warning Program • NWS AHPS Program • Water Project Management • Resource Management • Navigation • Drought Support • Recreation • Water Supply • 366 NWSRFS Forecast Basins • Flood Forecasts • Inflow/Streamflows • 74 COE/BoR Projects • ESP Forecasts • 147 WS Forecast Points • Volumetric / Peak Flow • December – July • Partnered with NRCS

9. NWS River Forecast System Precipitation Temperature Model Operations Observed Inputs Model Parameters Forecast Outputs Model States Deterministic Forecast Inputs (QPF) Deterministic Products

10. NWS River Forecast System:Calibration Mode Precipitation Temperature Model Operations Model Parameters Historical Inputs (40-50 yr record) Model Outputs Model States Statistical Summary

11. NWS River Forecast SystemDeterministic Forecasts

12. NWSRFS:Ensemble Streamflow Prediction Precipitation Temperature Model Operations Observed Inputs Model Parameters Ensemble Forecast Outputs (traces) Model States Ensemble Forecast Inputs (historical record) Probabilistic Products

13. ESP Trace Ensemble Plot 1987

14. 1989 1954 1959

15. Statistical Water Supply

16. Northwest River Forecast Centerwww.nwrfc.noaa.gov

17. www.nwrfc.noaa.gov Water Forecasts: 0 - 14 Days 14 - 120 Days Water Supply Peak Flow AHPS Watch & Warnings Flood Outlook Discussion Past Floods River Photos Dambreak Hydrologic Cycle Weather Snow Observations Forecasts Exp Forecasts Temp & Precip Forecasts

18. www.nwrfc.noaa.gov Water Forecasts: 0 - 14 Days 14 - 120 Days Water Supply Peak Flow AHPS Watch & Warnings Flood Outlook Discussion Past Floods River Photos Dambreak Hydrologic Cycle Weather Snow Observations Forecasts Exp Forecasts Temp & Precip Forecasts

19. www.nwrfc.noaa.gov Climate Climate Forecasts Drought Assessment Hazard Assessment Indexes Monthly Means Return Periods NWRFC Office Information Internal Web SDM Schedule Staff Employment Projects Papers Presentations Contact Us Links River Centers Weather Offices NWS Offices

20. 2005 Spring Outlook • New Service!!! • Ensemble Streamflow Prediction (ESP) • Issued for all Water Supply Forecast points • Updated weekly • Driven by Antecedent Snow/Soil Moisture • Does not incorporate climate forecasts (yet)

21. ESP Sensitivity Study:Summer/Fall Soil Moisture NWSRFS has a memory for soil moisture that extends many weeks into the future This memory can be exploited for the purpose of producing spring outlooks

22. Columbia River at Grand Coulee Snake River at Lower Granite Columbia River at the Dalles 29 108 Flow Volume (MAF) 30yr Ave 107 30yr Ave 30 67 30yr Ave 63 Jan-Jul Period 2005 Spring Outlook50% Exceedence Volume (MAF)

23. 2005 Outlook:Influence Late Summer/Fall Precipitation 30yr Ave = 30000 KAF

24. Recent Precipitation Precipitation Summary (Percent Average) AUG SEP OCT(1-18) SNAKE RV AB ICE HARBOR 192 125 126

25. ESP for 2004 (same period as WS) Water Supply 2004 ESP for 2005 “next year”

27. Using Climate Forecasts with ESP8 – 14 Day and Seasonal Forecasts Temperature / Precipitation

28. Taking Advantage of Climate Forecasts: ESP Pre-Adjustment Technique Climate Forecast Probabilities used to shift the distribution of ESP inputs (historical temp/precip record)

29. Taking Advantage of Climate Forecasts: ESP Post-Adjustment Technique • Yearly Weights applied to ESP traces • Weights are based on the similarity of a historical year to the current year • Can be used to exclude historical years

30. www.nwrfc.noaa.gov 5241 NE 122nd Avenue Portland, OR 97230 (co-located with Portland Weather Forecast Office) NWRFC: Website