Cold, Sun, & Wind Arrives Tomorrow

We’re about to see a somewhat dramatic shift in our weather pattern tomorrow through Friday or Saturday.  Say hello to sun, wind, and dry skin.  Say goodbye to fog, rain, and cloud cover.

Quite a surge of cooler and very dry air is moving through northern Washington this afternoon.  The dew point, a measure of the amount of moisture in the air, is falling like a rock in those places.  We’re already significantly drier here in the metro area this evening.  But Bellingham has dropped from 34 to 24 in just 3 hours, Spokane’s has gone from 30 to 12 in just 4 hours as the wind switched from west to north. 

All this dry air is headed down here into Oregon, so “skin-wise”, it’ll be the driest conditions we’ve seen so far this winter.  As you might guess, this means fog will only be patchy tomorrow west of the Cascades.

As the cold/dry air surges south through Eastern Washington, a very strong surface high pressure area develops over there, similar to a bathtub filling with heavy & dense water.  The only “drain” at sea level is the Columbia River Gorge; all that cold air will begin surging through the Gorge tonight and it’ll continue through Friday or Saturday.  Prepare for 3-4 days of strong easterly wind if you live at the west end of the Gorge.  Probably the coldest we’ve seen so far this year under sunny skies.  Here’s what we call a “cross-section” of the atmosphere for the next 3 days from the WRF-GFS model (UW) over Troutdale:

A few items:  The colors are relative humidity, clear is less than 50%.  Time goes from RIGHT TO LEFT.  The 10/12 refers to 4am this morning (Tuesday).  11/00 is 4pm today (right now), and 11/12 is 4am tomorrow, the 11th.  The far left side is Friday afternoon.  The bottom of the graphi is sea level and the top is 10,000 ft.  Notice the quick change as easterly flow commences right around 7pm in the atmosphere overhead, then it surfaces by daybreak out in the eastern metro.  By tomorrow midday, 45 kt easterly wind is just a thousand feet or so above the surface.  It’s going to be a big day out at Vista House.  Gusts in the western Gorge will be up around 60mph, with the usual 90 mph (or more) at the “Keely Chalmers Memorial Railing”.   This time around it’ll probably only be 35-38 degrees up there midday instead of 45-48.  Brrr!  I can’t make it this time around since I have a haircut at 11am…too bad.

The chart clearly shows bone-dry and clear through Friday afternoon.  A few high clouds may show up, but they will be higher than 10,000′, thus they don’t show up here.

More on the extended forecast on a following post.

Chief Meteorologist Mark Nelsen