24 Hours of Drizzle and Weather Models

November 14, 2010

The rain has not been continuous in Portland, but the gloom has…at home I’ve received about 1.00″ of rain today and a similar amount yesterday under a continuous onslaught of upslope rainfall out here.  It should let up some tomorrow.

So we’ve had 4 new runs of the GFS, and 1 new ECMWF run, plus some other assorted models.  What’s different for Thursday and beyond?  Not much…but models have definitely converged on a general solution through about 8 days.  Here are the highlights that I see:

1.  A major pattern change occurs Thursday and beyond…colder and a bit wetter, but not dramatically wet for November.  And I still don’t see a decent chance for low elevation snow in the next 8 days (through a week from Monday).  No model shows a big blast of arctic air either.  The ECMWF is the coldest with some 850mb temps down around -7 on Sunday, but then it’s dry.

2.  Nice mountain snow for Thursday behind a cold front; note snow levels late Thursday are as low as they are late Saturday, down around 2,000′, maybe a little lower.  That’s a nice chilly shot of air behind the cold front!

3.  No surge (or drift more likely) of colder continental air until Sunday, which means low level onshore flow prevails.  That plus 850mb temps around -4 Saturday and -5 Sunday mean snow would remain well above 1,000′ most likely.

4. Sunday-Monday should be dry as colder air filters down from the north.  Possibly dry Tuesday as well, but that’s 9 days away.  We should ALL get a nice hard freeze (25-30 in city and 20-25 outlying areas) if models are correct.

Chief Meteorologist Mark Nelsen