A Dry Weekend?

May 24, 2007

SnapshotSunshine all day long here in the western valleys…temperatures warmed nicely into the upper 70’s.  A weak push of northerly wind has been moving south through Eastern Washington tonight, much like an arctic front in winter.  Models show that turning flow easterly through the  Gorge by daybreak.  With a warm atmosphere still overhead, that should push high temperatures up a few degrees tomorrow.  My forecast could easily get screwed up by some high cloud cover keeping temps too low tomorrow.
Nice sharp trough swings through Saturday night through Sunday night.  This sets up a massive marine surge along with a cold upper-level atmosphere surging inland.  NAM showers showers in the chilly air Sunday afternoon, GFS does not.  I generally put more faith into the GFS, but a strong trough could give anyone a shower west of the Cascades.  I will be camping the first 2 days of the weekend in the Cascades…Sunday morning’s showers/drizzle at 40-45 degrees should be enough to chase me back home.
I’m much more confident on "the big warmup" beginning Tuesday.  All models (GFS, ECMWF, CANADIAN) have sharp ridging developing behind the cool trough.  A very nice thermal trough develops west of the Cascades Tuesday and continues at least through Wednesday.  East wind and 850mb. temps of +15 to +20 deg.C. will push temperatures up to or over 90 degrees in PDX-town in late May.  So IF the models don’t suddenly back off, we have quite a warm spell coming…Mark