April 18, 2012

We Win the Spring Weekend Trifecta!

Hard to believe...three decent weekends in a row...and the upcoming weekend, might be the best for some of you.

This last month has been very different form the sorry, soggy, chilly spring of 2011...April is roughly an inch drier than normal so far...and there is no sign that this pattern will change.

To begin, here is an interesting comparison between this year and last, showing you the actual temperatures at Sea-Tac and the average highs and lows.  Last year, we only reached normal highs a few times in March and never during the first 18 days in April.  This year (second plot) we have seen normal or higher temperatures several time in April...with a big high of 70F.  May seem subtle...but it makes a big difference.
Tomorrow should start out dry, but that will change during the afternoon when a warm front approaches western Oregon and then western Washington (see graphic of low level temperatures and winds).  In the graphic the warm front is indicated by the change from cold (green) to warm (yellow) and a wind shift from southeasterly to southwesterly.  Warm fronts are actually pretty rare around here...most of the time we experience old, weak occluded fronts.
Ok, we get some rain and the temperatures warm up for a while, and then a cold front moves through Friday morning, with more rain.   But by Friday afternoon things should start drying out as a ridge builds over the western U.S.  The issue is that the ridge line is a bit too far east to insure a completely dry weekend for the western side of the NW (see upper level map for Saturday morning), but except for the coast, we should see above normal temperatures and very little precipitation.  Eastern Washington and Oregon are sure bets.  The coast of Vancouver Island could be wet.

Here are the predicted temperatures from the UW model for 5 PM on Saturday...lower 60s in western Washington, while eastern WA and the Willamette Valley could get into the 70s.  Partly cloudy skies, with sky cover lessening during the day.

 And Sunday it gets even warmer, particularly over eastern Washington, where some folks will see the 80s.  Southern Puget Sound and the Willamette could reach near 70F.  But keep in mind that clouds will be moving in along the coast, and a modest error could ruin things for the west, particular during the afternoon.  On the other hand, if the band is bit farther offshore, inland western Washington could BURN! (low 70s).  Eastern WA should be solid in any case...that is where I am headed.

 My next blog will go to extremes....I will talk about the recent national poll on people's perceptions of trends in extreme weather.


  1. Yea! Maybe we will not have to edit our 2012 calendar for Mayuary, Juneuary -- like we did for the past couple of years :-)

  2. Interesting. Tonights GFS has 925mb and 850mb temps. in the 32 to 26C range for areas in Nevada and Utah. Thats really hot. Thankfully not this far up with our thick snowpack.

    CPC updated Mays outlook. Two shades of blue and of brown lol. The only state.

  3. Well yeah... yeah BUT.

    Here we are now on the first of May, and the weather people on TV are still droning on about temps 8-10 degrees below "normal".

    What is this "normal" anyway? Is it a rolling average? Over what time period?

    And if it is a rolling average, what does it say to the numerate that we are always below normal?



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