New Year Brings Big Gorge Wind

December 30, 2015

11pm Wednesday…

The sunshine has returned but so has the chilly Gorge wind.  Today the wind was just “average breezy”, but the next few days it’ll be a totally different story.

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Strong high pressure develops east of the Cascades Thursday-Sunday.  That means the pressure difference from eastside to westside dramatically ramps up the next 24 hours.  East wind increases as well.  That wind rushes through the one near sea-level gap in the Cascades; the Columbia River Gorge.  That’s why it’s called a “gap wind”.  The peak of the wind seems to be centered on New Year’s Day.  How windy?

MarkEastWind_ColdAirBuildsBasin

Those 65-80 mph gusts are for the usual windy places in the Gorge, not Crown Point.  Friday-Sunday should be 100+ mph days at Vista House.  It’ll be about 10 degrees colder than we typically see on these big wind days so you geeks headed out there better bundle up like you are in the Arctic!  In the metro area gusts 35-50 mph are likely Friday-Sunday from I-205 east.  Elsewhere, as always with a gap wind, the wind will be mainly light easterly, or at least less than 10 mph.

The WRF-GFS cross-section shows 50-60kt. wind just off the surface.  That’s just about the highest you ever see on these cross-sections:

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The chart was slightly “windier” for the Veteran’s Day Windstorm in November 2014.

I missed today’s high temp forecast by 4 degrees…it was 44 instead of 40.  I should have known better, the first east wind day when cooler air arrives is usually warmer than expected.  Then things settle down and the inversion settles in.  Temperatures drop a few degrees on following days.  Sure enough I notice areas in the wind tonight are running 2-3 degrees cooler than last night at this time.  So not only will be it windier tomorrow in much of the metro area, but it’ll be cooler as well.  Brrr!

I’m taking tomorrow off, so stay warm and have a safe and happy New Year’s Eve!

Chief Meteorologist Mark Nelsen


Northern Lights Possible Tonight

December 30, 2015

Very late tonight and again tomorrow night there is a chance you could see the aurora borealis or northern lights.  Note I wrote CHANCE.  I have still never seen them even after telling viewers multiple times that a CHANCE is on the way “tonight”.  Why?  Often they just appear for a few minutes or dozens of minutes at a time and then disappear.  Sometimes they don’t appear at all in our skies even though a geomagnetic storm is in progress.  Just to throw a number out there, if you were to go outside late tonight and stare up at the sky for 5 minutes out in the country…you probably have a 5% chance of seeing the northern lights.  Out of the ENTIRE night NOAA guesses we have about a 50% chance of seeing them at some point during the night.  Seems like aurora forecasting is about where weather forecasting was 100 years ago.

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As of 5pm the storm has not yet arrived.  So don’t even bother in the next few hours.  Keep an eye on www.spaceweather.com to see what’s going on elsewhere across the Northern Hemisphere.

You can find the latest planetary “K” index at this website:  http://www.swpc.noaa.gov/products/planetary-k-index

It’s a measure of geomagnetic storm activity.  When the level jumps to 6 & 7 that’s a big storm.  As of 5:30pm it’s all quiet and the storm has not arrived. Keep in mind that the times are in UTC…which is 8 hours ahead of us.  So we’re actually 1 hour 30 minutes into December 31st in UTC time…got it?

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Chief Meteorologist Mark Nelsen