Recap of Water Year 2008 Hydrologic Forecast and Forecasts for Water Year 2009

1. Recap of Water Year 2008 Hydrologic Forecast and Forecasts for Water Year 2009 • Francisco Munoz-Arriola • Alan F. Hamlet • Shraddhanand Shukla • Dennis P. Lettenmaier • JISAO/CSES Climate Impacts Group • Dept. of Civil and Environmental Engineering • University of Washington

2. Recap of WY 2008

3. ECMRWF ENSO anomaly 2008 European Centre for Medium-Range Weather Forecasts

5. Validation Plot for 2008 Forecast (All Cool ENSO composite) The Dalles Modified Flow (cfs)

6. April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies. 1916-2002

7. Natural Flows at Milner 1928-1989

8. Simulated Natural Flow at Milner (ESP all years) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations Natural Flow (KAF) Milner

9. Simulated Natural Flow at Milner (ESP cool ENSO) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations Natural Flow (KAF) Milner

10. WY 2008 Forecast

11. Potential Implications of ENSO Transition States WY 2007 WY 2008 WY 2009

12. ECMRWF ENSO anomaly 2009 0.2 -0.6 European Centre for Medium-Range Weather Forecasts http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/seasonal_range_forecast/nino_plumes_public_s3/

13. April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies. 1916-2002

14. Natural Flows at Milner 1928-1989

15. West-Wide Hydrologic Forecast

16. soil moisture snowpack streamflow, soil moisture, snow water equivalent, runoff local scale (1/8 degree) weather inputs INITIAL STATE VIC Hydrologic model spin up Hydrologic forecast simulation NCDC COOP station obs. up to 3 months from current index stn. real-time met. forcings for spin-up gap ensemble forecasts ESP traces CPC-based outlook NCEP CFS ensemble NSIPP-1 ensemble Observed SWE Assimilation SNOTELUpdate 25th Day, Month 0 1-2 years back Month 12 West-wide System UW Forecast Approach Schematic

17. Applications: climate forecast Ensemble Streamflow Prediction (ESP) recent met data to generate “perfect” ICs ensemble of historical met data to generate ensemble forecast Spin-up ICs Forecast observed hydrologic state

18. Soil Moisture and Snow Water Anomalies

19. April February March SWE and SM Simulated Climatological

20. February March April July August September SWE and SM Simulated Climatological

21. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Milner Climatology 1960-2005 All Years

22. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Dalles Climatology 1901-2005 All Years

23. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Milner Climatology 1960-2005 ENSO-Neutral Years

24. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Dalles Climatology 1901-2005 ENSO-Neutral Years

25. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Milner Climatology 1901-2005 3.4 Range 2009 -0.6 to 0.2

26. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes Based on Dalles Climatology 1901-2005 3.4 Range 2009 -0.6 to 0.2

27. West-Wide Hydrologic Forecast

28. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Milner All Years

29. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Dalles All Years

30. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Milner ENSO-Neutral Years

31. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Dalles ENSO-Neutral Years

32. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Milner 3.4 Range 2009 -0.6 to 0.2

33. Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) West Wide Forecast (1961-2000) Dalles 3.4 Range 2009 -0.6 to 0.2

34. UW Forecast System in the Snake River Hells Canyon Dam Milner

35. UW Forecast System in the Hydropower-related stations at the Columbia River Grand Coulee Chief Joseph Dam

36. Conclusions: • Cool ENSO event during the winter of 2007-2008, increased above average Apr-Sep flow at Milner • High snowpack during winter-spring was associated with low values in soil moisture • The WY 2008 ESP forecast predicted increased likelihood of wet conditions. Observed summer flows at Milner in 2007 were above average (~25% of normal for April-Sept) • Current soil moisture conditions may contribute to slightly reduce streamflow generation during the Jan-June period by 3%. • The west-wide forecast system predicts flows similar to those observed in the climatologies for the Dalles , However for the Milner stations there is a increased likelihood of drought and consequently flows slight below normal for the coming water year. • Slightly below 1961-2000 climatological values • Slightly above -0.6-to-0.2 ENSO neutral values • On the average of ENSO neutral years

37. Potential Implications of ENSO Transition States WY 2007 WY 2008

38. Historic Dalles Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO WY Std Ann. Stats: 12 of 13 above 0.39 11 of 13 above 0.49 9 of 13 above 0.88

39. Based on Dalles Climatology 1901-2003 Natural Streamflow (cfs)

40. Historic Milner Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO WY Std Ann. Stats: 5 of 7 above 1.1 3 of 7 above 1.7

41. Based on Milner ESP 1961-2000 enso_2008 enso_trans_2008 Natural Flow (KAF) Natural Flow (KAF)