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Climatic Perspective on the fall/winter of 2004-2005 Nathan Mantua, Ph.D. University of Washington Climate Impacts Group

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Presentation on theme: "Climatic Perspective on the fall/winter of 2004-2005 Nathan Mantua, Ph.D. University of Washington Climate Impacts Group"— Presentation transcript:

1 Climatic Perspective on the fall/winter of 2004-2005 Nathan Mantua, Ph.D. University of Washington Climate Impacts Group http://cses.washington.edu/cig April 6, 2005 -- CIG Seminar

2 The good news The winter of 2004-05 has finally ended! It’s been snowing in the Cascades From the Mt Baker ski area web-cam (10 am, Sunday March 20th)

3 Western Snowpack March 1st Northwest snowpack situation was bleak on March 1st http://www.wcc.nrcs.usda.gov

4 Western Snowpack April 1st The NW snowpack situation has “improved” (as of April 5th)- yet still extremely poor by historical averages

5 How did we get here? the low snowpack occurred largely because of warm temperatures during the periods when most of our precipitation occurred: December 6-10 and January 17-19

6 Fall and winter storms have generally been too warm to develop this year’s snowpack 22% 52%

7 (as of April 6, 2005) White-Green-Puyallup: swe-38%, pcp 61% Cedar-Snoqualmie-Skykomish Tolt: swe-29%, pcp 70% Baker-Skagit-Nooksack: swe-45%, pcp 85% 33% 85%

8 seasonal averages of precipitation and temperature are not exceptional. Most locations in Washington have received 65-80% of normal precipitation since October 1. This is considerably more than in 1977 or 2001. Temperatures also have been only about 1F above normal. Precip % of normal since Oct 1

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10 Precipitation and Snow- water-equivalent for Seattle City Light’s key watersheds: the Skagit and Pond Oreille http://www.ci.seattle.wa.us/li ght/ctracks.html

11 Snowpack update for Seattle’s Water Supply Basins http://www.seattle.gov/util/ About_SPU/Water_Syst em/Water_Supply/

12 Seattle Public Utilities Water Supply Update

13 Why? The proximate cause was a large number of days with a split jet stream around a blocking ridge located over the NW region Was it El Niño? –Definitely not “typical” of past El Niño events Ocean temperature anomalies Jet stream wind patterns R

14 Oct 2004-Feb 2005 200mb ht anomalies The tropical atmosphere has been warm!

15 Are we in a situation like the early 1990s with multiyear warmth in the western eq. Pacific?

16 Oct-Mar 91-95 200mb ht anoms Oct-Mar 02-05 200mb ht anoms

17 Oct-Mar 91-95 SST anoms Oct-Mar 2002-05 SST anoms

18 \ From NCDC’s 2004 Annual Climate Report http://www.ncdc.noaa.gov

19 SST anomalies for the past month

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23 summary It has been a warm and dry winter, but not of “record” extremes in either temperature or precipitation The tropics have been very warm, yet not in a “classic” El Niño pattern –part of longer term and broader scale atmospheric warming? Official CPC forecast calls for increased odds for a warm spring

24 CPC forecast for July-August- September 2005 Temperature Precipitation

25 SeaTac’s precipitation

26 Daily temperatures at Sea Tac


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