Very Brief Warm Spell

April 11, 2008

Snapshot Snapshot2_2
I’m torn this evening; which is better, a beautiful sunny day tomorrow, or a brand new episode of Battlestar Galactica on at 10pm?  At least in this case I can have both.  Well, obviously I’ll be recording episode #1 & #2 of this final season since I have a little job to get done from 10-11pm.  I screwed up last week when I forgot to set the VCR to Daylight Time.  Amazing that I can get a weathercast together isn’t it?
  A nice warm 69 degrees at PDX today, the warmest so far this season and right around the 68 I forecast for today.  We did this without much of any easterly flow, some light easterly drift down the Gorge, but that was it.  Quite a change by morning though.  Mesoscale models say up to 5 miliibars easterly gradient in the 7-10am timeframe.  This gives us much better mixing of the warm/dry atmosphere above.  According to the April "Magic Chart", offshore flow+850mb temps 11-12 deg = a maximum as high as 80 tomorrow at PDX, with 75-78 most likely.  So I’ve bumped up the high temp forecast to 77, assuming that we’ll be between 74 and 80 (I consider a 3 degree margin of error acceptable).  Whew…lots of numbers.  For the regular person, it just means a perfect mid-June day is on tap for Saturday!
  Models are all in agreement in bringing a dying cold front inland Sunday.  Our model here holds off rain until the evening.  Then it’s back to cool, showery, and "troughy" weather the rest of next week.  The big picture looks like this:  the weekend will only be a brief intermission in our cool & wet spring so far.  Mark Nelsen