Mountain Weather Forecast

Weather Synopsis

The persistent west coast ridge fends off the storm track through Friday but succumbs to a stronger frontal system approaching Friday night and impacting the area on Saturday. Thursday's fizzled shortwave brought little more than widespread cloud cover to NW Washington, with sunny skies for most other mountain areas. The ridge will briefly rebuild late Thursday night with some cooling associated with the aforementioned shortwave. By Friday, freezing levels rebound back to 9,000-12,000 ft across the region as milder air moves in on increasing SW flow with a chance of isolated showers for the west slopes of the Olympics or Mt Baker areas. During the is time, low clouds/fog will stay locked in for deep valleys, especially along the eastern slopes of the Cascades and near the Cascade Passes. Winds above and below the inversion will be decoupled with generally WSW and light winds above the inversion and E flow below. Snoqualmie Pass remains the only location with moderate E winds at Pass level which are expected to decrease very slightly as time progresses.

The drastic shift in the weather begins Friday night. A low moving toward Heida Gwaii sends a moisture-laden and reasonably sharp frontal boundary toward our region. Most areas will see precipitation start as rain up to around 8000 ft with snow levels dropping following precipitation onset. Steadier precipitation arrives with moderate to locally strong SW winds for the Olympics and Mt Baker areas in the late evening and spreads into the central Washington Cascades overnight, becoming moderate to heavy for the west slopes and Cascade passes. Rain and snow peak Saturday morning with snow levels still near or above the Cascade Crest.  Sharper cooling during the mid-day hours returns snow to middle elevations with significant accumulations expected.