Mountain Weather Forecast

Weather Synopsis

An approaching short-wave system is knocking on our door this afternoon and has already spread clouds and stronger winds across much of the region. While you may see a few isolated sprinkles near Mt Baker or Wa Pass before sunset, most of the precipitation will hold off until the evening or overnight hours. Look for rain and snow to spread from north to south as the storm steadily slides down along the spine of the Cascades. You'll see three very noticeable trends as the storm approaches and passes.

1. Strong and gusty W-NW winds will develop in many locations. For some of our more wind-prone sites like Mission Ridge, Crystal Mt, and Mt Hood you may experience very strong winds as the main precipitation bands approach.

2. Temperatures will sharply cool. While many locations may start this event as rain, it should quickly turn to snow. That includes Stevens and White Passes. At Snoqualmie expect more of a rain-snow mix as the snow level fluctuates near or just above pass level. 

3. Light to moderate rain and snow will focus near and west of the crest. A very pronounced rain shadow will cause precipitation totals to decrease significantly the further east you travel. 

By Friday morning, the bulk of the storm will focus on the southern WA Cascades and Mt Hood. Northerly flow aloft will start to usher in drier air behind the front. This should quickly bring an end to lingering showers with the region drying from north to south. Low-level moisture could keep the west slopes a bit drippy, but up in the mountains, you may see a few sun breaks especially in the Olympics and North Cascades. 

We should see a brief pause in the action Friday night. However, a strengthening arctic front will pass over the area Saturday and bring us a chance of snow primarily from near I90 southward. Since this storm will approach from the NNE, it doesn't have much moisture but very cold temperatures will result in even a little precipitation turning into several inches of low-density snow.