Evening Wind Update

November 16, 2009

Okay, last one for today.  Strong upper-level wind is surfacing nicely during the last hour central/western Metro area.  The stubborn easterly flow out of the Gorge just won’t give in on the far eastside near the Columbia River.

The main reason I believe we are getting a lot of mixing down is the dewpoints in the 30s and temps in the 60s!  That’s pretty dry air considering we are just south & east of a warm conveyor belt of heavy rain moving into the north Coast Range and western Washington.  Also notice the pathetic 7 millibars EUG-OLM gradient.  That only gives peak gusts 25-30 mph at face value.

Strongest wind should be in the next few hours as the cold front approaches.  Hope we don’t get any surprise 50-60 mph gusts!

Oh, and it looks really wet the rest of the week.  Many inches of rain in the mountains and an inch or two the next few days in the lowlands…yuck.

Chief Meteorologist Mark Nelsen


Afternoon Wind Update

November 16, 2009

The 2nd wave of wind appears to be arriving on the Coast late this afternoon as the deeper low approaches.  It’s ratcheted back up at Astoria and down the Coast in Lincoln County.  We can see blowing sand on our Chinook Winds Beach Cam now;  it wasn’t doing that about an hour ago.

Here in the Valleys it looks like peak gusts have been a notch or two above 40 mph in a few places.  We’ve had 41 mph here on the roof of the “Palace KPTV”.  More wind this evening with the strongest wind likely around cold front passage time, before midnight.  I still don’t expect any of the regular reporting sites to see gusts above 50 mph.

Chief Meteorologist Mark Nelsen


Morning Update

November 16, 2009

I just scanned all the latest info with the morning coffee.  I don’t see anything that alters my midnight post reasoning.  Maybe the strong wind ends a bit earlier along the Coastline…all finished by 10pm possibly?  The low is too far north for strong wind (50+) here in the Valleys.  The curl does show up nicely in the IR loop though.  Out at the Coast the wind should slacken a bit the next few hours, then really pick up 4pm-8pm for the final push.

Chief Meteorologist Mark Nelsen


Coastal Windstorm Tomorrow!

November 16, 2009

It’s late Sunday evening and after 24 hours out of town I return to changed weather maps.  Looks like the strongest windstorm of the season so far is on the way for the Oregon/Washington Coastline, not so much for the inland areas.  junk

You definitely want to click on the image to get a larger view on this one.  It’s a cross-section of the atmosphere over one location as time moves through the next 72 hours.  Time moves from RIGHT TO LEFT.  So Sunday evening is on the far right side and Wednesday evening is on the left.  Specifically this is model forecast data over Newport, OR from 4pm today to 4pm Wednesday.  The WRF-GFS mesoscale model from UW.  The colored areas are relative humidity, and you see temperature contours in celsius in red.  What you really want to notice is the wind barbs though.  They are in knots, so you have to do the 1.15 x Knots to get the mph.  Notice over Newport that 850mb wind is from the S-SW over 50 kts from about now until Tuesday morning, peaking out around 100 mph around midnight or so tomorrow night!  We haven’t seen a forecast of 850mb wind this strong since the December 2007 storm.  The wind over the western Valleys is up around 50-70 mph during that period. 

What you want for a really good windstorm is a strong surface pressure gradient to go with it.  A deep surface low is going to track along the cold front offshore tomorrow evening and end up on Vancouver Island late tomorrow night.  Some of the evening models a bit more of a “double-low” structure, others just one.  Either way it’s deep enough (975-980mb) to get strong winds to surface along the Coast but too far away for a big windstorm in the Valleys.  I notice the EUG-OLM gradient is relatively weak, maybe 10-12 mb. at best tomorrow night.  That would only equate to surface wind gusts 30-40 mph at best.  But add the strong wind up above AND warm airmass for decent mixing so I could see 40+ gusts at all the airport observing sites here in the metro area, maybe a 50 mph at SLE and UAO.  It’ll be tough to get higher than that though unless we get a freak line of convection with the cold front.  I’d like to see a deeper low, like we had in 2006, and much better east/west alignment of isobars in the Valley.  Something to keep an eye on;  it’ll be interesting to see if we get a “westside enhancement” with the peak gusts like we did in the December 2, 2007 storm.  Remember how it was windy for 24 hours straight on the westside of the metro area (Hillsboro, Beaverton etc..) but much lighter wind eastside due to the strong southeasterly gradient?  Strongest wind here should be sometime between 8pm-2am.

Along the Coast I think all the cities could get gusts 60-70 mph.  With the proliferation of home weather stations in exposed sites along the coastline, it seems that any decent storm nowadays produces a gust 70-80 mph SOMEWHERE.  So I’m sure we’ll hear about a gust of 95mph either at a mountain location or Cape Meares or one of those spots.  But this should be a good storm for lots of 80mph gust reports.  Strongest wind at the Coast should be 6pm-Midnight.  Gentlemen…start your generators!

Chief Meteorologist – Mark Nelsen