1. Northwest River Forecast Center Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for the 2011 Water Year Steve King, Hydrologist Stephen.King@noaa.gov

2. Topics for Presentation  Overview of Water Supply Models used at the NWRFC  Recap of WY 2010  2011 Volumetric Streamflow Outlook  Direction of NWRFC Water Supply Program

3. NWRFC Water Supply Models  Statistical Water Supply  Seasonal Volumetric Forecasts Statistical Regression techniques (Legacy, SWS)Statistical Regression techniques (Legacy, SWS) Based primarily on observation (Runoff, Snow, Precip)Based primarily on observation (Runoff, Snow, Precip) NWS Driver for ‘Official’ Federal Coordinated ForecastsNWS Driver for ‘Official’ Federal Coordinated Forecasts  Ensemble Streamflow Prediction  Many types of forecasts including Seasonal Volumetric Forecasts Probabilistic (ESP) technique built on top of real-time hydrologic modeling systemProbabilistic (ESP) technique built on top of real-time hydrologic modeling system Combines updated model states with QPF and weather scenarios (typically based on climatology).Combines updated model states with QPF and weather scenarios (typically based on climatology).

4. http://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi http://www.nwrfc.noaa.gov/espws/espws.cgi Seasonal Volume Forecasts (2010 Example) http://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi http://www.nwrfc.noaa.gov/espws/espws.cgi Statistical Water Supply ESP Volume Forecasts

5. Water Supply Release Schedulehttp://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi

6. WY 2010 Seasonal Precipitation Above Grand Coulee ~ 92% Above Lower Granite ~ 95% Above The Dalles ~ 96%

7. OCT 09NOV 09DEC 09 JAN 10FEB 10MAR 10 APR 10MAY 10JUN 10 JUL 10AUG 10SEP 10

8. OCT 09NOV 09DEC 09 JAN 10FEB 10MAR 10 APR 10MAY 10JUN 10 JUL 10AUG 10SEP 10

9. WY 2010 Runoff Recap http://www.nwrfc.noaa.gov/runoff/runoff.cgi Snake/ Lower Granite 75% Columbia/ The Dalles 79% Columbia/ Grand Coulee 77% Westside = Apr-Sep Eastside= Jan-Jul Palisades Inflow 75% Boise River 80% Owyhee Inflow 77% Dworshak Inflow 73% Jackson Lake Inflow 75% Salmon River 98%

10. Verification of Fall Outlook (WY 2010) Snake/ Lower Granite 75% Columbia/ The Dalles 79% Columbia/ Grand Coulee 77% 2010 Observed Runoff Snake R Lower Granite 96% 90% Columbia The Dalles 95% 91% Columbia R Grand Coulee 96% 91% ESP Outlook w/o ENSO ESP Outlook w/ ENSO

11. 2010 Forecast Verification http://www.nwrfc.noaa.gov/water_supply/ws_verif.cgi

12. 2010 Forecast Verification http://www.nwrfc.noaa.gov/water_supply/ws_verif.cgi

13. Spring 2011 Outlook  Ensemble Streamflow Prediction (ESP)  Driven by: Antecedent Snow/Soil Moisture 10 day Precip and Temp forecast Precip and Temp climatology (1948-2002)  Published forecasts updated weekly  Capability of including climate forecasts/signals (unpublished)

14. Forecast input to ESP: Precipitation, Min and Max Temperature, Freezing Levels 6hr QPF available for day 1-3 24 hr Quantitative Precipitation Forecast for days 1-10 http://www.nwrfc.noaa.gov/weather/10_day.cgi

15. 2011 Outlook* (ESP Forecasts) ttp://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi 50% Ex. Prob = 29 MAF 97% of 30 yr Norm (30 MAF) 50% Ex. Prob = 103 MAF 96% of Normal (107 MAF) * Reflects current model states (antecendent conditions),10 day QPF, and climatology

16. 2011 ESP Outlook* Snake R/ Lower Granite 89% Columbia R/ The Dalles 93% Columbia R/ Grand Coulee 96% Jan-Jul Median Ensemble Volume Percent of ESP Normal * Reflects 10/26/10 model states,10 day QPF, and ESP climatology Palisades Inflow 102% Boise River 102% Dworshak Inflow 96% Salmon River 110%

17. SST Predictions (Oct 2010) SST observation and forecasts indicate that we are in a strong La Nina climate pattern that is expected to persist through the first half of 2011.

18. CPC Seasonal Winter Outlook Dec-Jan-Feb WY 2010 Outlook (issued last fall) WY 2011 Outlook (current)

19. CPC Seasonal Winter Outlook Dec-Jan-Feb WY 2010 Outlook (issued last fall) WY 2011 Outlook (current)

20. 2011 ESP Outlook Using La Nina Climatology Snake R Lower Granite 89% 97% Columbia The Dalles 93% 96% Columbia R Grand Coulee 96% 102% ESP for ALL years ESP for La Nina years Median Ensemble Volume Percent of ESP Normal La Nina Climatology DJF ENSO ONI <= -1.0 11 cases in ESP record (1948-2002) WY 1951 1955 1956 1965 1971 1974 1976 1985 1989 1999 2000 Palisades Inflow 102% 114% Boise River 102% 109% Dworshak Inflow 96% 110% Salmon River 110% 125%

22. v v http://wateroutlook.nwrfc.noaa.gov

23. NWS Western Region / NWRFC Water Supply Directions  No operational changes for WY 2011  Examine potential for ESP as primary forecast tool.  Replace Legacy Raw model with SWS as supplementary forecast tool.

24. WS Model Verification Study 2009-2010 SWS similar to and often better performing than other models ESP stronger than others for late season forecasts

25. NWS Western Region / NWRFC Water Supply Directions  Work with users to determine forecast locations and forecast periods that are providing the most value for users.  Expand use of QPS in ESP  Investigate conversion of regulated forecasts to unregulated (natural) streamflow forecasts.

26. Northwest River Forecast Center www.nwrfc.noaa.gov