Monday, November 28, 2011

Climatologically, The Worst of Winter is Over!

Yes, you read that right.

The last week or two of November is climatologically the worst period of the year by many measures.   For example, consider the average precipitation per day at Sea-Tac Airport (below).  It peaks in last November and most of December is a drier.


Or how about extreme daily precipitation at the same location?


Big peaks in November and a radical reduction in extreme precipitation in December. 

Just like clockwork there is going to be a major break in the coming up this week, but first we have to get through one more storm. A low center and accompanying clouds and precipitation is moving towards us from the northwest and should bring precipitation to the region late tomorrow and Wednesday AM.  You can see it off our coast in this satellite image:


This system should be unremarkable. After that a very strong ridge will build northward into the eastern Pacific and will remain in place for at least a week.  You heard me...a week.

Like Wednesday morning

Thursday morning


 Friday morning
Saturday morning


You get the idea.  And we will have lots of sun...and some fog in the AM.  The biggest threat to your life and safety will be ice on the roadways.  Will we have another big storm...of course we will. And a good chance of some lowland snow.  But ON AVERAGE things typically improve as we move out of late November into December.

The National Weather Service has this regime going into next week...here is their latest 6-10 day precipitation forecast:  below normal in the West.


 This looks like a good time for local meteorologists to go on vacation.  Or to rake some leaves.

PS:  I know "official" winter starts on December 22 and ends in March.   The point is that calendar winter is really quite different than meteorological winter in many parts of the country...and we are a good example of that.    Around here the end of February could really be considered the end of winter....sun is much stronger, far less weather systems, chance of flooding goes to near zero, etc.  And the grass starts growing again on the west side of the Cascades.  When I have to mow my lawn, winter is over..period.

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