Windy Start…Now the Snow

December 19, 2007

Snapshot Snapshot2I was pleased with the windspeed forecast both on the Coast and in the Valleys.  Looks like peak gusts here in the valley were near or below 40 mph (yes, I know Salem was a bit higher).
Coastal wind seems to have maxed out 50-60 mph in the cities (Newport, Tillamook, Astoria).  But the recent standouts were there once again…The hill east of Cape Meares at 1400′ hit 77, the radio tower in Lincoln City up around 200′ elevation hit 76, and the Yaquina Bay Bridge was 72 mph.

Now it’s time to talk snow…the radar is full of rain moving through the metro area at 4pm headed for the Cascades…can’t wait to see the live shots from the evening newscasts (including on FOX12).  Now that the flow at 850mb. turns westerly, the snow should really pick up in the Cascades due to orographic lifting.

About 10-13" has fallen with this current storm and another 12" or so should fall by the time things die down tomorrow evening.   The snow level dips down to around 1,500′ tomorrow afternoon, then possibly down to 1,000′ or a bit lower tomorrow night.  Unfortunately, the precipitation appears to shut off quickly around sunset, so that’s why I’ve really pooh-poohed the chance for lowland snow tomorrow night.

The next system rushed in Saturday morning; I wouldn’t be surprised to see a minor "Forest Grove Effect" if the precip arrives before 10am.  That’s due to a sharp east-southeast flow ahead of the front piling up some cold air against the Coast Range.  Just a possiblity, but something to watch for since the UW-MM5 hints at it.  That will be system #1 of the new round.  #2 comes in Sunday night and Christmas Eve morning.  #3 arrives Christmas Day late.  The 12z/18z GFS were quite cold behind each system, with snow down to 1,000′ or so Christmas Eve, then even lower the morning after Christmas.  The ECMWF was not quite as cold.  I noticed it had -5 deg temps at 850mb.  That wouldn’t bring snow as low.  So now the 00z GFS comes in with slightly warmer air behind the Christmas Eve front, and significantly more reasonable temps for the day after Christmas…plus it pushes the timing on that front a bit later too.
So…I think we’ll flirt with low elevation snow (to the foothills) both periods, but I still see no decent chance for lowland snow.  Too much westerly flow with cold fronts flying through the Northwest about every other day, not a good chance for cold air to get established.

The big picture shows an almost continuous parade of storms through the New Year…lots more weather fun.  I’ll be on vacation now through Christmas Day, so probably no blog posts until the 26th.  BUT, for those of you expecting a big weather event while I’m on vacation???  Unlikely since I will be in town taking care of Santa Claus duties for a few days.  I could be in here with a moment’s notice!  Mark Nelsen

More later…Mark Nelsen