Mountain Weather Forecast

Weather Synopsis

The high-pressure ridge parked in the eastern Pacific will keep us dry for one more day ahead of an approaching storm. On Thursday expect mild temperatures, strengthening winds, and increasing clouds. Just how much sunshine you see will likely depend on how far south you are in the forecast region. Areas near and south of I-90 will have the best chance of blue skies, while locations further north should start the day with significantly more clouds. Either way, look for clouds to increase, thicken, and lower. The bigger story today could be the winds. We're already seeing many stations showing moderate winds with much stronger gusts. This pattern will continue as wind speeds strengthen ahead of our next storm tonight. 

While you could encounter a few stray sprinkles near the Canadian border late this afternoon, in general, precipitation should hold off until overnight. A short-wave system will slide down the backside of the high-pressure ridge and spread light to moderate rain and snow from north to south across the mountains. More importantly, as precipitation arrives, so too does much colder air. So, while some locations may start as rain, cooling temperatures should quickly cause it to change to snow. The one exception could be Snoqualmie where snow levels will fluctuate right at or just above pass level. Due to the orientation of this storm and poor forcing dynamics, there should be a very pronounced rain shadow effect with precipitation totals decreasing significantly the further you travel east of the crest. 

Precipitation will linger into Friday morning. As the system continues down into Oregon, it will finally take aim at Mt Hood, Mt Adams, and Mt St Helens. Further north, look for showers to taper and winds speeds to decrease from north to south. By the afternoon, drier air will start to move in behind the storm and you could even see a few sun breaks in the North Cascades and Olympics.