Spring Weather, Winter Temps

March 8, 2010

That title refers to the sunshine and showers we are getting this afternoon.  The strong March sunshine is giving us some nice convective spring-like showers this afternoon, all while under a cold airmass.  I just had snow flurries (maybe some graupel mixed in) at 45 degrees!  It was light and there was no rain, just small flakes floating down.  So obviously the “warm” air we are seeing at ground level this afternoon is very shallow.  The next few hours could give us more sun, hail, thunder, graupel, or even all snow.  That’s what I had mentioned in the middle paragraph of Saturday’s post.

I’m home taking a rare sick day today…a bad man-cold.  I could be near death and I sound kinda like that, so it’s best to stay home instead of infecting everyone else.  Plus tomorrow is a long day with 4 school visits down the Valley starting at 7:30am.  Let’s hope that there is no need for me to head in to work tomorrow afternoon for Mar-ch-arctic Blast ’10. 

After our pop-up showers die down this evening we clear out for awhile…models keep insisting on some sort of cloud cover later tonight with even a few flurries possible around daybreak.  Looking at the satellite picture it seems more likely that we’ll just stay clear and get very cold…25 in the coldest outlying spots and closer to freezing here in the city.

Skies cloud up tomorrow afternoon and steady precipitation from an approaching cold front arrives by 5pm at the latest.  Models have been very consistent with the timing; especially our RPM and the WRF-GFS from UW.  This gives about 6 hours (9am-3pm) for temps to warm into the 40s.  There is no source of cold air to the east, although we don’t get a southerly wind up the Valley either.  The combo of those two leads me to believe we’ll top out in the mid 40s tomorrow afternoon, then fall back to around 38-40 at the lowest elevations from evaporative cooling.  If you go up to the top of the West Hills or anywhere else above 1000′, it’s more likely it’ll start falling as all or mostly snow.  I still think that for most of us it’ll be tough to get sticking snow below 1,500′ tomorrow afternoon/evening.  If the system came rushing in at 9am after the cold night I’d be more excited.

There are several places where I think the snow level could be closer to sea level tomorrow evening (1-3″ possible).  Far Western Washington County and Columbia Counties: Forest Grove, Banks, Vernonia.  The central Columbia River Gorge: Cascade Locks and Hood River Valley.  Maybe the Lewis River Valley areas too (above Woodland, Yacolt etc…)

I should point out that my very first thought about tomorrow was “will it be a repeat of December 29th”.  I looked at the soundings and meteograms I saved…it was quite a bit colder that day in the lowest part of the airmass.

Enjoy the weird snow/hail/sun this afternoon

Chief Meteorologist Mark Nelsen