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Northwest River Forecast Center

Northwest River Forecast Center. Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for the 2011 Water Year. Steve King, Hydrologist Stephen.King@noaa.gov. Topics for Presentation. Overview of Water Supply Models used at the NWRFC Recap of WY 2010

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Northwest River Forecast Center

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  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) • Based primarily on observation (Runoff, Snow, Precip) • NWS 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 system • Combines updated model states with QPF and weather scenarios (typically based on climatology).

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

  5. Water Supply Release Schedule http://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 09 NOV 09 DEC 09 JAN 10 FEB 10 MAR 10 APR 10 MAY 10 JUN 10 JUL 10 AUG 10 SEP 10

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

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

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

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

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

  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 OutlookDec-Jan-Feb WY 2010 Outlook (issued last fall) WY 2011 Outlook (current)

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

  20. 2011 ESP Outlook Using La Nina Climatology 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 ESP for ALL years ESP for La Nina years Median Ensemble Volume Percent of ESP Normal Columbia R Grand Coulee 96% 102% Dworshak Inflow 96% 110% Snake R Lower Granite 89% 97% Salmon River 110% 125% Columbia The Dalles 93% 96% Boise River 102% 109% Palisades Inflow 102% 114%

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

  22. 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.

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

  24. 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.

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

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