Storm #1, on to #2

January 18, 2010

A nice little storm last night with peak gusts over 80 mph on the coast (expected), and 40-60 mph gusts in the western valleys (unexpected).  Luckily I can claim I was having fun with extended family this weekend; only briefly looking at maps Saturday evening and again last night around…11pm.  So this is one of the times I somewhat “checked out” of the weather scene.  Not a big storm by any means, BUT enough to equal our peak gust of 51 mph at PDX so far this winter.  Looks like there were never more than 10,000 PGE customers out of power, always a good measure of the strength of a metro area south wind event.  Remember the “minor” Dec. 14th, 2006 storm?  That put 250,000 customers out of power! 

This IS a fun weather pattern with deep lows approaching the West Coast and then making a left hand turn.  Fast-moving systems too.  Did you notice how quickly we went from gusty southerly wind last night to a gusty easterly wind today in advance of the next low?  The downsloping flow warmed us up into the 50’s today…some spots up near 60!  Now it feels like a real El Nino setup with major storms into California and a mild January so far up here.

Tonight’s forecast is tricky for storm #2.  Another deep low is just west of Cape Mendocino this evening, a bit farther south and east than forecast by the WRF-GFS.  Supposedly this one (and the following one on Wednesday) don’t move as far north, leaving Washington in easterly gradient at all times.  Northern Oregon barely gets into the “south wind zone”.  In fact when I first walked in this afternoon my thought was “how are we going to get a south wind up the valley tonight?”.  There is little to no southerly pressure gradient at the surface up the valley overnight, even less than last night.  By the way, did anyone notice the peak gradient EUG-OLM last night was only around 8 millibars?  That’s generally a peak gust forecast of 30 mph or so at PDX!  Obviously we overachieved due to strong wind above, a mild airmass, and good mixing due to those heavy showers central/west side of town.  So due to that we decided to say gusts to 35 mph from the south for just a few hours in the middle of the night tonight in the metro area as the south wind punches through briefly…then it’s back to easterly by early morning again.

Another deep low moves up the coast on Wednesday.  The problem is that models don’t/aren’t handling the low pressure centers well (last night’s and apparently now today’s).  So I don’t believe any one model solution.  We’ll take things day by day.

One thing far more certain is a real lack of significant rain this week.  The firehose is aimed and southwest Oregon and California.  Washington barely gets anything this week.

9:30PM Update:

Stormy weather is just a couple hours away on the Central Coast.  What’s going on seems much more clear now based on satellite and model info.  The main low is pretty much modeled in the correct position out near 130W.  But the earlier low (which I thought WAS the main one) is now whipping around (dumbelling) the main low.  It’s so close to the Coast near Coos Bay that it’s almost touching…can’t be more than 30 miles offshore.  It’s now heading north quickly, and should be at Newport 2 hours from now.  Apparently this is the trough (kink in the isobars) seen on the last two WRF-GFS model runs.  Except the model didn’t know there is a closed low instead.  The low passed very close to Buoy #46015 (it’s actually working!), with a pressure around 977 mb.  With this low racing north off the coastline overnight, I feel very good about south wind gusts to 70 mph out there…almost as strong as last night.  Here in the Valley I agree with the NWS putting out a Wind Advisory for the South Valley.  But I think gusts of 40-50 mph are likely a little farther north?  More like anywhere south of Portland.  I see the WRF-GFS has 25 kt. wind all the way up into the southern Metro area with only the weak trough swinging through.  With a closed low it’ll probably be a bit stronger.  So I’m going to adjust a graphic or two up on windspeed.

Chief Meteorologist Mark Nelsen