Mountain Weather Forecast

Weather Synopsis

An atmospheric river is steering moisture and rising snow levels into our region this afternoon. Stormy conditions will intensify as a strong cold front approaches and sweeps from NW to SE across the area tonight, bringing heavy precipitation and strong winds across the mountains. Temperatures will remain mild through the evening and then snow levels will drop rapidly after the cold front sweeps through the Cascades in the 1-2am window.  

We'll be left in post-frontal westerly flow on Wednesday, with snow (finally!) showing up at lower elevations (2-3000') and stacking up throughout the day.  Snow totals through Wednesday afternoon should range from 6-18".  The west slopes of the Cascades, the Passes (above 4000'), and areas near the Cascade crest are the most likely places to see a foot or more of new snow. Westerly winds will be so strong that a clean convergence zone may be hard to discern on radar, but there may be stretches of E-W convergence bands in the Mt Loop and Stevens vicinity, particularly through mid-day Wednesday. Extreme winds will be a theme this afternoon and tonight just about everywhere.  Ferocious westerly winds will not let up on Wednesday, at least not immediately, and strong downslope winds will pepper not just the mountains but also ares along the eastern slopes of the Cascades during the day. Both showers and winds will taper slowly later in the day. 

Showers should be lighter on Wednesday night as a new Pacific frontal system approaches.  The heaviest precipitation and winds will push into the Mt Hood area early Thursday, and lighter but still significant precipitation will spread northward as an occluded front approaches the WA Cascades Thursday afternoon.  There will be some warming with this system, but outside of Mt Hood, it's unclear how much snow levels jump over the Cascades Thursday afternoon and evening.