Monday, December 21, 2015

The Wettest December in Northwest History?

We are two-thirds through December and MONTHLY ALL-TIME precipitation records are already being broken.


This morning, Portland Oregon broke its all-time monthly precipitation record for December.   The wettest December on record At 6:53 AM their total December rainfall was 13.52 inches, exceeding the previously monthly record of 13.35 inches.  Since then Portland has had another 2/3 inch.  And there is a third of the month left!  The record there is going to be smashed.  Not even close.

Astoria has received 18.68 inches so far, in second place to the 20.38 inches in 1996.   They will easily gain first place in a few days.

Salem, Oregon has been pummeled by 13.68 inches, behind third place 14.03 inches, observed in 1917.  Beating that is in the bag. Second place is 15.01 inches in 1996.  Well within reach.  First place is 17.54 inches in 1933.  A stretch, but possible.

Seattle is closing in on major records as well. The SeaTac record over a period of 70 years (1945-2014) is 11.85 inches observed in December 1979.    Even without a drop of additional precipitation, we have achieved the third wettest December:

1) 11.85      1979
2) 10.18      1996
3) 10.03      2015 (as of 6 PM today, Monday)

There is a very high probability that we will surpass second place (1996) within the next day and have a good shot of besting the 1979 total of 11.85 inches by end of the month.  

The last few weeks have been amazingly wet.  Here is the percent of normal precipitation for the last 14 days.  Oregon and southern Washington has received 200 to 400% of normal rainfall for that period, with some places in eastern Oregon hit by over 400% of normal.

For western Oregon and the southern portion of western Washington, this is going to be the wettest December on record.

To live through the wettest December in Portland or Seattle is really saying something.  Something you can talk about when you are 90.  Or not.

And with cool temperatures, snow is piling up.  Here is the latest SNOTEL percentage of normal snowpack (snow water equivalent) for Washington.  Much of the state is over 100%, with 161% of normal over the Olympics.


But what about Oregon?  Crazy snowy, with the southern and eastern portion of the state with over 150% normal snowpack.


As an aside the official drought monitor shows extreme drought over eastern Oregon (see below).  Very strange.

Released December 17th

 Our reservoirs are full or nearly full.  Our snowpack is great.  Life is good.  Especially for local ducks.


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