Saturday, November 2, 2019

Rain Returns to the Northwest

It has been extremely dry during the past week over the Pacific Northwest, and dry conditions will continue into Thursday.

But by the weekend, the rain will return. 

Dry periods extended into the first week of November is not that unusual in western Washington and Oregon, but for it to continue into the second and third week would be  extraordinarily unusual.   And this won't happen this year.

Let's forecast the right way, looking at ensembles of many forecasts.  Below are the 21 members of the  U.S. GEFS ensemble.   The accumulated precipitation of each member at Sea Tac is shown. Precipitation is flatlined for all members until November 7th, after which there is a steady rise.  This is called a plume diagram by the way, with each line being one member.

 What about the more skillful and larger (51 members!)  European Center ensemble?  A similar story, but presented a different way--a stripe for each forecast, with the colors indicating the 24-h precipitation amounts.  Neither system is indicating a  large amount of precipitation at Sea Tac.


The precipitation total through 4 PM Saturday shows the heaviest precipitation is going into southern British Columbia, but with several inches extending into northern Washington State.  Unfortunately, temperatures will be too warm to result in much snowfall in Washington.


5 comments:

  1. Looks like you may have spoken too soon.

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  2. The rain will return just not anytime soon. Ridge-zilla is the main feature for the foreseeable future folks. Get used to it.

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  3. Yup. The Ridge continues. Might break some records soon. If this were the age of sail there would be dead horses floating in the Salish Sea.

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  4. BAMCIS: I think "record-setting" is grossly over rated, particularly in rain shadow zones. In terms of the pattern of seasons this year's fall was early, with significant lows similar to some late Novembers and even early Decembers. Inland and to the north we've only had just over one dry week. In the last fifty days here near Mt Baker our daily precipitation averaged .20" per day - an inch every five days - which is extremely wet compared to other recent years. "Just saying" that whatever happens at SeaTac I think the Pacific Northwest is far from dry right now.

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