1 Climate recap and outlook Nate Mantua, PhD University of Washington Center for Science in the Earth System - Climate Impacts Group Vancouver, WA October 2, 2008 Nate Mantua, PhD University of Washington Center for Science in the Earth System - Climate Impacts Group Vancouver, WA October 2, 2008

The CSES - Climate Impacts Group Goal: help the Pacific Northwest become more resilient to climate variations and climate change Supported by NOAA Climate Program Office as part of the Regional Integrated Science and Assessments (RISA) program Goal: help the Pacific Northwest become more resilient to climate variations and climate change Supported by NOAA Climate Program Office as part of the Regional Integrated Science and Assessments (RISA) program

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5 Accumulated Precip for the past year Source: html

6 Accumulated Precip for the past year Source: html December 3rd storm

7 Seattle Times, Dec 17, 2007 Chehalis River Flooding at Centralia, WA Seattle PI, Dec 5, 2007

8 Daily Temperatures -0.67ºC

9 A big snow year for the Cascades Mark Stoelinga at his Skykomish Cabin January 31, tml Elev 3500ft

10 Summer ocean conditions upwelling downwelling

Coastal Upwelling - Area below (above) black line indicates climatological upwelling (downwelling) season. - Climatologically upwelling season progresses from March to July along the west coast of North America from 36ºN to 57ºN. -Figures provided by Yan Xue, NOAA NCEP Winter downwelling was weak; upwelling was strong in April, May, and June, but weak in July- August

12 Coastal ocean temperatures were cold from winter through July

13 Oct 2007-June 2008 SST anomalies: La Niña and a cool phase of the PDO

14 Land and Ocean temperature anomaly was +0.72°C ( climatology), 8th warmest in 129 years

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16 Pacific Climate Outlook Summary from Oct 2007 forecasts rated La Niña as most likely situation for PDO: Transiting to cool phase as La Niña fades forecasts rated La Niña as most likely situation for PDO: Transiting to cool phase as La Niña fades European Center Forecast summaries

17 Typical winter climate pattern jet stream during past La Niña winters

18 Last Year’s forecast: Wet Autumn and winter, Equal Chances on Temperature Temperature Precip OND DJF

19 Fall-Winter US climate of

20 Blame the circulation pattern observed 500mb height anomalies from Dec 2007-June 2008 shows a persistent region of high heights in the Gulf of Alaska and low heights over south-central Canada … H L

21 Blame the circulation pattern At left is a “composite” for the last 8 La Niña periods … a close match to pattern

22 This year?

23 Observed SST anomalies September 21-27, 2008

24 La Nada Tropical ocean temperatures have generally returned to long- term averages

25 Equatorial subsurface ocean temperature anomaly Colder than average waters in the east indicate a shallow thermocline, favoring additional cooling in the near term

26 The latest ENSO forecasts See European Center Forecast summary

27 PDO forecast: drifting toward neutral territory -- index has been negative since last September From June-July-August 2008 initial conditions ml

28 Another factor in seasonal forecasts PNW December-January-February temperatures

29 30-day climate forecast: expect a cool-wet beginning to fall (from Sept 30, 2008) See

30 CPC Forecasts from Sept 18, 2008 precipitation temperature

31 The Bottom line expectation for ENSO-neutral conditions, combined with recent trends, favors “Equal Chances” for fall-winter precipitation and a small increase in the odds for warmer than average temperatures – ENSO neutral and La Niña years tend to favor major flood events Additional influence from PDO might offset another factor… – Persistent warming trends expectation for ENSO-neutral conditions, combined with recent trends, favors “Equal Chances” for fall-winter precipitation and a small increase in the odds for warmer than average temperatures – ENSO neutral and La Niña years tend to favor major flood events Additional influence from PDO might offset another factor… – Persistent warming trends See

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35 Sept 30 estimated soil moisture percentiles Courtesy of Andy Wood, University of Washington, data and images are available at Courtesy of Andy Wood, University of Washington, data and images are available at

36 Daily Temperatures -0.67ºC+0.03ºC-0.64ºC