Ellensburg, just to the east of Snoqualmie Pass (see red A on map), is a really windy place in the summer. I mean windy. A listing of the winds (in knots, 1 knot=1.15 mph) and other weather is show below for the 24 h ending 1 PM today (times are in UTC--same as GMT). Strong northwesterly winds were evident (270 is west, 360 is north, etc), with gust to 34 knots (39 mph). And this occurs day after day. I have also included a plot of the sustained (2 minute average) winds and gusts for the last few days. Day after day of this stuff.
Why is Ellensburg so windy? The topographic map below shows the reason...a weakness in the Cascades (called Stampede Gap). During the summer, pressure is higher on the western side of the Cascades and lower over the heated basin of eastern Washington, with the pressure difference increasing during the day as temperatures soar over eastern Washington. Air accelerates from high to low pressure and it finds the weakest location...in this case Stampede Gap, where the terrain is only 3-4k feet high. Air accelerates through the gap and spreads out over the Kittitas Valley, with northwest winds on many summer days gusting to 30-40 mph.
This area is so windy that it is an excellent place for wind turbines....and you can see several wind projects on the ridges above the valley (such as the Wild Horse project on Whiskey Dick mountain). The strong NW winds are also apparent in some parts of Cle Elum, including the trendy Suncadia Resort. I stayed there one night....they should call the place Windcadia Resort. The golfers there were having a tough time, with their balls flying in unexpected directions in the gusty air above the ground.
If you want more on this topic, I have a section in my book, which also describes similar effects in the Columbia Gorge.
