Wind Arrives Tonight

January 25, 2007

Snapshot_10A dramatic change in progress at this hour, although you sure can’t tell if you look out the window.  East wind is just arriving at the west end of the Gorge and will push out into the metro area by daybreak.   The pressure gradient through the Gorge from PDX-DLS has gone from +2.0 millibars (westerly) to -2.4 mb (easterly) at 11pm.  Models show a good 6-8 millibars by tomorrow morning, which should give us enough wind to wipe out the fog and low clodus in the metro area.  That should be the last of the gray skies for quite some time.  I put the image to the left in for your viewing.  It shows clearly how the Columbia Gorge wind really is a "gap" wind.  If you drive from Gresham to Sandy you’ll notice the east wind almost always disappears around Boring.  Same thing on a drive from E. Vancouver or Camas up to Battleground.  The wind remains close to the river, especially right where it exits the Gorge.  This also shows that when Battleground or Sandy gets a strong easterly wind, it’s clearly coming down off the Cascades, not coming around from the Gorge.

Pattern from tomorrow through day 7 at least has a sharp and strong ridge sitting just offshore of the West Coast.  Cold northerly flow remains well to the east into the middle of the country, but close enough to keep surface high pressure east of the Cascades.  This should give us a long period of gusty east wind and low dewpoints/relative humidity.  00z GFS is a little "waffley" on the ridge later next week, but ECMWF & GEM are more persistent with ridging.
One interesting question to be answered will be; is this the beginning of a many-week long "El Nino" pattern?   Or for the rest of the winter?  Or is it just a short intermission in our stormy winter?  Anyone have any ideas?  Mark