Mountain Weather Forecast

Weather Synopsis

A ridge of high pressure brings us one last mild night before we move into a cooler regime into early next week. Freezing levels remain unseasonably high (9000-12000 ft), but an east-side cold pool below 5500 ft, moderate E flow, and valley subsidence will keep main mountain locations below freezing. A rapidly moving front approaches with high clouds lowering and thickening Thursday night. Winds increase into the moderate range for the mountains of NW Washington and light rain and snow arrive in the early morning hours for the Olympics.

Given the dry air in place, snow levels rapidly lower with the onset of moderate rain and snow early Friday morning with most places near and east of the Cascade Crest receiving snow above 4000 ft, while areas further west experiencing snow levels around 4500-5000 ft rapidly dropping to 3000-3500 ft. Expect a quick 3-6 hour shot of steadier precipitation, followed by a frontal passage. The frontal passage should switch low-level winds westerly and could bump snow levels up to 3500 ft temporarily at Snoqualmie Pass before snow levels re-descend to 3000 ft late in the day.

We're keeping our eyes on the potential for convergence bands from the southern Mountain Loop to Mt Rainier Friday afternoon through Saturday evening. At the moment, the exact locations of these bands are tricky to pin down, but expect locally heavy snow within the wider array of light post-frontal snow showers targeting primarily the west slopes of the Cascades. Moderate to strong W winds peak during this time and focus on the mountain gaps, east slopes of the Cascades, and Mt Hood.

Additional most very light snow showers continue on Saturday with NNW flow on the back side of a broad trough. Temperatures should near or below seasonal norms from Friday night onwards.