Strong Easterly Winds Hit the Northwest

Powerful winds have pushed through and downstream of regional gaps in the Cascades and other regional mountain barriers.

Consider the maximum gusts observed this morning (see below).  

There are three swaths of wind exceeding 40 mph (yellow colors).  One extends southwest of Bellingham and heads over the San Juan islands and then westward out the Strait.

The other extends westward north of Mount Rainer and out to Tacoma.  And another extends from the western Columbia Rivr Gorge and then over Portland and the northern Willamette Valley.


There are a few odd strong winds over some exposed ridges, like one near the Tri-Cities.

So what is going on here?

We start with a very large difference in pressure across the Cascades.  Sea level pressure (solid lines) and near-surface temperatures (color shading, blue and purple indicated cold air) for 4 AM this morning are shown.  

There is a very large pressure difference (gradient) across the Cascades with higher pressure to the east.   Cold air is denser than warm air, resulting in higher pressure near the surface east of the Cascades.


This difference in pressure drives winds, which accelerate from high to low pressure.

But there is a problem.  The Cascades block the air at low levels!  

Thus, air looks for gaps or weaknesses in the Cascades to push through, and as shown in the topographic map below, there are three of them.

One gap encompasses the Fraser River Valley and exits near Bellingham.  Another is the Columbia River Gorge, a near sea level gaps across the Cascades.  And the final one is the Stampede Gap southeast of Seattle which represents a weakness or lower area in the Cascades.


These three gaps represent favored conduits for air pushing westward from eastern Washington.

An exciting development is the growing ability to skillfully forecast the strong gap winds using high-resolution regional models.  

To illustrate, below is a 24-h forecast of the winds exiting the Fraser River gap this morning at 4 AM. You can see the swath of strong winds over Bellingham and the San Juans.


Finally, there is the issue of gap-wind tourism.  Where is the best place to experience the regional gap wind phenomenon?

My recommendation is Crown Point in the Columbia Gorge, with the Vista House being the perfect venue.  They even have a snack bar!


The winds have gotten over 100 mph at this location.  This morning it got to 74 mph.

What could be better than being buffeted by hurricane-force winds and then enjoying a hot chocolate?  For a meteorologist or weather enthusiast, nothing could be better.


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