Mountain Weather Forecast

Weather Synopsis

A very active weather pattern will continue over the next several days as incoming storms interact with an entrenched cold air mass over the region.  Eventually, the cold air over area will moderate, but not without twists and turns and bouts of wintry mixed precipitation.

A sharp upper level trough will pass through Cascades this afternoon. This will bring strong westerly ridgeline winds down to Pass level and temporarily mix out the strong temperature inversions due to east winds and bring an end to localized freezing rain near and east of the Cascade Passes. The heavy snowfall many areas are seeing this afternoon will become focused on the Mt Hood area this evening. Post-frontal showers along the west slopes of the Cascades will quickly become scattered later this afternoon and largely fizzle into the evening. Strong westerly winds will also ramp down after midnight over the WA Cascades.  

Strong arctic high pressure anchored over the front range of the Canadian and northern US Rockies will drive a reinforcing shot back across the Cascades tonight. A warm front will lift from south to north across the area on Thursday, hanging up across the south Washington Cascades. Light snow will be found along both sides of the Cascades with increasing snowfall rates south of I-90 and down near Mt Hood. Strong SE ridgeline winds will keep the tap of cold air from eastern WA coming...and the precipitation type as all snow except the Olymipcs where mixed precipitation may occur. 

Another frontal wave will rotate up similarly on Thursday night and Friday. This round should feature stronger SW winds aloft which will reintroduce the potential for freezing rain back into the picture for the Mt Hood area Thursday night, and the central and southern Cascades on Friday. Some areas will start to see their freezing levels "pop" as warm air rides in aloft on Friday.