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Hydrologic outlook for the Pacific Northwest in Water Year 2008

Hydrologic outlook for the Pacific Northwest in Water Year 2008. Andy Wood Xiaodong Zeng and George Thomas Alan Hamlet and Dennis Lettenmaier Dept. of Civil and Environmental Engineering for Climate and Water Resource Forecasts for the 2008 Water Year UW Climate Impacts Group

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Hydrologic outlook for the Pacific Northwest in Water Year 2008

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  1. Hydrologic outlook for the Pacific Northwest in Water Year 2008 Andy Wood Xiaodong Zeng and George Thomas Alan Hamlet and Dennis Lettenmaier Dept. of Civil and Environmental Engineering for Climate and Water Resource Forecasts for the 2008 Water Year UW Climate Impacts Group October 2, 2007, Olympia, WA

  2. Presentation Outline 1. Introduction: UW Experimental Hydrologic Forecasting System 2. Water Year 2007 Discussion and 2008 Outlook

  3. IntroductionUW Seasonal Forecast System PI: Dennis Lettenmaier, UW Sponsors: NOAA CPPA program, UW CSES www.hydro.washington.edu/forecast/westwide/

  4. Experimental W. US Hydrologic Forecast System Snowpack Initial Condition Soil Moisture Initial Condition

  5. ESP 1960 1961 1962 … … 1999 ENSO subset Can adjust IC by assimilating snow or other observations Hydrologic Model-based Forecasting recently observed meteorological data ensemble of met. data to generate forecast Spin-up Forecast ICs* hydrologic state obs IC = initial conditions

  6. Streamflow Forecast Results: West-wide at a Glance

  7. Clicking the stream flow forecast map also accesses current basin-averaged conditions Applications: streamflow Hydrologic Analyses Flow location maps give access to monthly hydrograph plots, and also to raw forecast data.

  8. Presentation Outline 1. Introduction: UW Experimental Hydrologic Forecasting System 2. Water Year 2007 Discussion and 2008 Outlook

  9. The PNW hydrologic cycle • soil moisture near annual low • runoff near low • nearly all water year precipitation yet to come • snow season not really underway • evaporation not a factor Average annual water cycle PNW * Where we are now on average

  10. The PNW hydrologic cycle Note that there is variability in soil moisture now… current

  11. Recap WY2007, Dec. 1 hydrologic conditions Soil Moisture SWE

  12. Recap WY2007, Jan. 1 hydrologic conditions Soil Moisture SWE

  13. Recap WY2007, Feb. 1 hydrologic conditions Soil Moisture SWE

  14. Recap WY2007, Mar. 1 hydrologic conditions Soil Moisture SWE

  15. Recap WY2007, Snow Obs & Simulation Observed SWE

  16. Recap WY2007, Apr. 1 hydrologic conditions Soil Moisture SWE

  17. Winter 2006-07:seasonal volume forecast for APR-SEP OBS Forecasts made on 1st of Month

  18. Slides Since Apr 1, 2007: • late summer precip was low • one heat outbreak (in July) • soil moistures have dropped • entering new water year with a deficit

  19. Oct 1 Soil Moisture Comparison with Last Year THIS YEAR LAST YEAR

  20. La Nina versus Normal conditions: Oct, Nov, Dec precip temperature SWE soil moist runoff oct nov dec

  21. La Nina versus Normal conditions: Jan, Feb, Mar precip temperature SWE soil moist runoff jan feb mar

  22. La Nina versus Normal conditions: Apr, May, Jun precip temperature SWE soil moist runoff apr may jun

  23. La Nina versus Normal conditions: Jul, Aug, Sep precip temperature SWE soil moist runoff jul aug sep

  24. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Dalles: 92 / 101

  25. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Priest Rapids: 95 / 103

  26. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Snake: 82 / 96

  27. Snake: 82 / 96 • low soil moisture depresses flows through June • La Nina compensates, especially in June & July

  28. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Upper Snake: 85 / 97

  29. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Waneta: 91 / 101

  30. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Arrow: 99 / 106

  31. Forecast initialized Sep 23 ‘07: Summer Volumes Forecasts of April-September 2008 Flow ESP ESP: La Nina Mica Dam: 99 / 106

  32. Mica: 99 / 106 • no soil-moisture hangover • La Nina yields higher flows in June – Sept. • but lower flows in Apr-May

  33. hydrologic outlook • Columbia R. (The Dalles): near normal about + 5% to north about - 5% to east or southeast (Snake) • wide uncertainty ranges about these forecast averages Summary current soil moisture deficits in eastern half of basin La Nina tendencies toward wetter and colder climate early season forecast

  34. questions?

  35. This Year’s forecast initialization

  36. Continental US Forecast for Soil Moisture

  37. Slides

  38. Slides

  39. Slides 1. Introduct

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