Strong East Wind & Sunshine Ahead

November 25, 2012

The next two days will feature a mix of SUN & WIND for the Portland/Vancouver Metro area.   Our first real chilly and strong gorge east wind of the season is here and will continue through Wednesday.  Just the beginning of lots of cold winter wind!

Then it’s back to lots of gray and rainy weather systems moving in off the Pacific Ocean as we enter a new storm cycle.

An upper level ridge is moving overhead during these next two days.  At the same time surface high pressure is building to our east rapidly this evening.  Pressures are rising over the lower elevations of Eastern Oregon and Washington and falling west of the Cascades (slowly) this evening.  As a result an easterly pressure gradient is growing quickly, already approaching 6 millibars at 9pm from Troutdale to The Dalles.  This is well ahead of even the mesoscale model forecasts of a 6-8 mb gradient during the daytime tomorrow.  It’s a nice “cold pool” developing in the Columbia Basin, the first one of the winter season.  What does this mean?  Wind gusts have already reached about 45 mph at Corbett and they’ll easily touch 60 tomorrow and/or Tuesday out in the western Gorge.   Probably gusts around 35-40 mph in Troutdale and 25-35 mph anywhere east of I-205 near and south of the Columbia River.  This is strictly a gap wind event, not a downsloping wind, the amount of wind you get will be directly related to how close you are to the west end of the Gorge.  So most of Clark County will see mainly calm conditions (away from the Columbia).  Same with anywhere south of Tigard/Oregon City or west of Beaverton.  Wind does tend to whistle over the top of the West Hills and come down the west slope there.  Places like Bonney Slopes, Providence St. Vincent and Sylvan get real windy in this pattern.

As several deep low pressure areas approach the coastline late Tuesday and into Wednesday, the pressure falls west of the Cascades will keep the wind going.  We also get a much warmer airmass OVERHEAD tomorrow and Tuesday.  This means a sharp inversion.  East wind events in the Gorge are helped out by a sharp inversion.  In fact the strongest east wind episode of the past 10 years at the west end of the Gorge was with 850mb temps up around +15 in early January 2010, yet high temps were only in the upper 40s in the metro area.    This doesn’t look anywhere near as strong, but still, a lot of raging east wind in the Columbia River Gorge and east metro area the next 3 days.  And it won’t totally go away until next weekend.

Important Note:  The Vista House wind sensor has been offline for about 6 weeks; there was flooding or some sort of water issue in the basement where the sensor/computer are kept and they haven’t gotten it all cleaned up.  Sensor is fine, but office space is not.  It is also illegal to walk down to Vista House for one more month due to a road closure at Larch Mtn. Road.  The next strongest windspeed is at the Corbett Grade School here:

For the areas NOT in the east wind zone, we’ll get patchy areas of dense fog overnight along with some freezing temps.  Even though the airmass will be too dry for fog just a few hundred feet up with the dry wind moving in, there should be enough moisture for that fog.

Chief Meteorologist Mark Nelsen