Mountain Weather Forecast

Weather Synopsis for Wednesday night through Friday

The unseasonably cold and active pattern should continue through the end of the week...with periods of lowland snow continuing.

A deep, powerful, and cold low pressure reaches peak intensity (~975mb) several hundred miles off the Washington Coast. The track of the low will create a strong E-W pressure gradient, sucking strong E winds through the mountain gaps that peak late Wednesday afternoon into the early evening. Winds in the 20-30 mph range are expected through Snoqualmie Pass with moderate to strong winds notable more for their gusty nature (50-60 mph possible) throughout Cascade Foothills. At the Cascade crest level, the associated front should bring increasing strong to very strong SSW through SSE winds as it approaches during the evening hours. The southerly flow aloft tends to block Snoqualmie and Stevens Pass and ESE low-level flow dries out as it descends over the West Central Cascades, reducing snowfall there as well. The front has reached the Washington Coastline at 2:15 PM and should cross the Cascades shortly after midnight. Winds should decrease overnight as the deep low moves away and weakens as it tracks northward into a blocking dome of cold, Canadian air. Light to moderate snow shower activity should continue through the day on Thursday with a trough offshore spinning cold, unstable air into the region.

At cold temperatures, low-density snow should add up Wednesday night and Thursday with 1-2 ft likely in locations favored by the SE low-level flow and southerly flow aloft. These include the E slopes of the Olympic Mountains, Mt. Rainier area, and Mt. Baker area. 

Thursday night, the upper trough moves over the region with and shifts eastward on Friday with light snow shower activity tapering as a subtle ridge builds Friday afternoon.