Cold & Windy

December 2, 2006

Everything is proceeding according to plan…east wind has arrived across the metro area, blowing out the fog & clouds.  Easy forecast for tomorrow is sunny with any fog confined to west of I-5 and only briefly in the morning.

PDX-DLS gradient picking up dramatically late this afternoon as the airmass in the Columbia Basin is cooling;  8 millibars at 4pm.  The Dalles, smothered under low clouds, only made it to 33 degrees today with light easterly wind.  The cold airmass eastside is only about 2000′ thick (it never really gets deeper than 4000′.) but that should increase to over 3000′ by tomorrow.  It’ll be interesting to watch Redmond’s obs in the next 24 hours.  Today it hit 41 degrees (RDM is at 3,100′), but if the top of the cold airmass makes it up to there tomorrow, it’ll only be about 20 and foggy.  The thickening of the cold airmass combined with a dramatic warming of 850 mb. temps tonight means the air flowing through the Gorge get’s "squeezed" down into a thin layer of chilly air shooting out the west end.  The pressure gradient should go up to 10-12 millibars by midday tomorrow then relax to under 8 again by Monday morning.  I see peak gusts are over 50 mph now at Corbett Elementary School and they should see a few gusts to 70 mph by midmorning Sunday.  That sensor goes out easily because even a brief power outage of a few seconds kills it until someone comes back on Monday for school.  Anyone else in Corbett or the hills east of Washougal have a weather sensor AND DSL connection?  Email me if you do.

This sort of pattern generally doesn’t push wind far out into the metro area as I mentioned last night.

I’ve put rain back into the 7 Day forecast for Monday afternoon-Tuesday as a weak system temporarily flattens the ridge.  Of course with such a chilly airmass coming through the Gorge freezing rain is definitely in the cards.  I doubt it’ll be cold enough for Freezing Rain even at Troutdale.  You’ll have to head to Multnomah Falls on I-84 or up above 500′ or so above Washougal or in Corbett for that.  Interesting though that the system moves through a ridge, so there’s no dislodging of the cold air.  Could the Gorge see freezing rain that doesn’t melt or just briefly tries to melt and then Wednesday the ridge locks in the cool air again?  So much weather fun…Mark