1. Climate Review for WY 2004 and Outlook for WY 2005 Philip Mote Climate Impacts Group University of Washington Annual Fall Forecast Meeting October 26, 2004 Boise

7. Oct 2003 - Feb 2004 US Climate % Normal Precip Temperature (Deg F)

8. March 2004 US Climate % Normal Precip Temperature (Deg F)

9. March-April 2004: a west coast ridge that would not quit 300 mb height anomalies (meters): March-April 2004

10. Water Year 2004 US Climate % Normal Precip Temperature (Deg F)

11. NOAA-CPC climate outlook from last fall: climatological odds for fall/winter PNW precip in spring 2004 odds tilted in favor of above average precip. (forecast from August 17, 2003)

12. NOAA-CPC climate outlook from last fall: climatological odds for fall/winter/spring PNW temperatures (forecast from August 17, 2003)

13. Summary: NW climate in water year 2003-04 Overall a warm and slightly dry water year; average precipitation from Oct-Feb, then a very warm and dry March. –The water year as a whole was warm/dry throughout most of the western US CPC forecasts from last August called for “climatological odds” for fall/winter/spring precipitation and temperature –The tropical Pacific was just slightly warm, so forecasts called for “ENSO neutral” conditions (neither El Niño or La Niña) in the tropics

14. A history of ENSO 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 warm cool warm A history of the PDO

15. tropical ocean temperatures: a weak El Niño is underway

16. Equatorial Ocean Temperature deviations from the long-term average: 1982-September 2004 82/83 86/87/88 91/92 97/98 02/03 EN 93 94/95

21. Multi-model forecast summary

22. Ocean temperature anomalies August 15-September 11, 2004

23. The PDO has been less prominent since the early 1990s- present From Bond et al. 2003, Geophysical Research Letters, Vol 30: 2183-2186. 195019601970198019902000 2 leading patterns of North Pacific SST since 1950 PDO “Victoria Pattern”

24. PDO index Victoria pattern index The PDO pattern was strong from 1950s through the 1980s The Victoria pattern was strong from the 1990s through 2003 In the winter of 2003- 2004, the North Pacific was warm, yet the pattern of warmth did not resemble either a PDO or Victoria pattern From Bond et al. 2003, Geophysical Research Letters, Vol 30: 2183-2186. Phase plot for the 2 leading patterns of North Pacific wintertime SSTs (5 yr avgs) 50s-mid70slate 70s/late 80s

25. Wintertime SST anomaly patterns 1990-97 1999-02 2003

26. Pacific Ocean Outlook Summary Current forecasts rate a “weak to moderate El Niño” as most likely situation for fall-winter PDO? –A simple forecast with skill relies on “PDO persistence + ENSO influence” Expect weak to moderate warm phase PDO conditions for fall/winter (PDO = +0.5 to +1 st devs for Nino34 =.4 to 1.2) Other? –consistently warm ocean temperatures in the far N. Pacific have not been captured very well by the PDO index in the period from 1990-2002

27. Nov temp

28. DJF temp

29. JFM temp

30. FMA temp

31. Nov precip

32. DJF precip

33. JFM precip

34. NOAA/CPC forecasts issued September 16, 2004 FMA precip

35. Summary and Conclusions Expect a weak to moderate intensity El Niño for this winter NOAA CPC forecast for NW –Increased odds for a warm fall and winter; equal chances wet or dry for Idaho Extreme cold, low elevation snows, and extreme flooding have been less frequent than average in past El Niño winters in the PNW region

36. Climate information International Research Institute for Climate Prediction http://iri.columbia.edu Western Regional Climate Center http://www.wrcc.dri.edu NOAA’s Climate Prediction Center http://cpc.ncep.noaa.gov Office of the Washington State Climatologist http://www.climate.washington.edu Idaho State Climate Services http://snow.ag.uidaho.edu