Much Warmer Week

April 2, 2007

SnapshotThis week’s forecast has been changing for the warmer the last 24 hours (on KPTV at least).  I just adjusted the numbers upward for Thursday and Friday based on the 00z GFS, ECMWF and UW-MM5.
First, the cold…clear skies, briefly calm wind, and dry/cold airmass overnight should allow most areas west of the Cascades to drop below freezing by daybreak.  High pressure is settling in east of the Cascades overnight and models show at least 4 millibars pressure difference from DLS to PDX by morning.  That’s gusts to 40 mph at the west end of the Gorge that will spread out across much of the metro area by midday, then die down tomorrow evening.  East wind this time of the year will warm us up nicely, but the warming will be tempered by lots of high cloudiness from an offshore system.
That will be the story this week (the high clouds) as we will be on the western periphery of a large warm upper-level ridge centered over the Western USA.  Systems will just scrape the west Coast on their way north.  It appears the later Thursday and Friday the ridge will briefly push back to the west, directly over us.  Latest 00z GFS and the old 12z ECMWF have 850 mb. temps over Portland up to +11 or +12 C.  That, combined with offshore flow, should easily push temperatures into the mid 70’s for the first time this year.  With perfect conditions a +12 can get us to 80 degrees in April…it’s looking warm either way!  Mark