Mountain Weather Forecast

Weather Synopsis

We're in for a stormy night in the mountains north to south and east to west. You could encounter very strong and gusty winds combined with moderate to heavy snow. The front edge of a wide precipitation band is already pushing inland from the coast this afternoon. A low-pressure system will stall just offshore this evening and spin moisture up into the mountains from the S. Look for increasing winds and snow to spread from SSW to NNE overnight. With primarily SE-S winds, this storm will buck the typical Pacific Northwest norms. Moisture will rotate around the Cascades and should produce significant snowfall along the east slopes of the range. Locations from Mission Ridge to Ahtanum Meadows will likely see more precipitation than the Cascade Passes. This flow pattern also favors the volcanoes, where more 1 to 2 ft of snow should quickly accumulate overnight. 

On Saturday the Low will slowly meander its way southward. This should allow wind speeds to gradually decrease and precipitation to wane for most areas. However, upslope showers will continue to favor the same locations along the east-side forecast zones and the volcanoes. The weather models continue to struggle with this pattern, so if you find yourself under one of these bands of snow, you could see locally moderate to heavy precipitation. 

The storm finally exits our region and we slowly begin to dry our Saturday night. Even still, an unstable atmosphere may allow a few showers to linger in the mountains. Things get tricky from there. Locations near and north of I90 appear to continue to dry. However, the low pressure (now well to our south) tries to send one last round of moisture rotating up into the Cascades. There's a lot of uncertainty with this feature, but it could provide just enough to keep the snow falling across the southern half of the forecast area.