Strong Push of Marine Air into the Washington and Wildfire Threat Along the Cascade Eastern Slopes

As I write this, a very strong surge of cool, cloudy marine air is pushing into western Washington, bringing gale-force winds to the Strait of Juan de Fuca and dry/windy conditions along the eastern slopes of the Cascades.

The latest satellite photo (8PM Thursday) shows the coast inundated with low clouds, with tongues of cloud pushing eastward both north and south of the Olympics. 

In the Strait of Juan de Fuca, winds gusted to 56 mph at Race Rocks, near Victoria (see map of maximum gusts since midnight).  41 mph at Smith Island, just off of Whidbey Island.

If you live in Puget Sound country, your wind chimes are either sounding or soon will.

Some of the incoming cool air is pushing up, over, and down the eastern side of the Cascades, accelerating as it moves towards lower pressure in eastern Washington--as shown in the chart above and the blow-up below.   Some favored locations from Ellensburg to Yakima are hitting 40 mph or more.  Lots of wind for the wind energy facilities.

This air descending the eastern slopes of the Cascades is quite dry.  To illustrate, here is the relative humidity analysis at 5 PM Thursday.  Under 30% in much of eastern Washington, while moist air was pushing into the coast.  You got to love a state with such large humidity contrasts.

The combination of dry conditions and strong winds provide a fire threat along the eastern slopes of the Cascades and portions of the Columbia Basin...so folks need to be careful.   Very similar conditions produced the 243 command fire near Wanapum Dam just last week. 

The US Forest Service has created a graphic than combines a wind and dryness as a tool to estimate fire threat.  This graphic...called Hot/Dry/Windy... shows the risk area noted above.  Kind of ironic that the biggest wind/wildfire threat occurs when cool air is moving in.