Mountain Weather Forecast

Time and Day: 0900 Monday

The Snapshot: Continuous light snow today, becoming moderate this afternoon. Repeat for Tuesday with heavier snow amounts Tuesday night and Wednesday morning. 

The Science: A cool and blustery day at Stevens Pass. 4” in 24 hours continues the trickle-in trend. As the trough moves east today, NW upper level flow will bring moist and cool air across the forecast area maintaining convergence type showers and gusty winds. There should be a brief break Tuesday morning, although we may not even notice it. Skies will remain cloudy and the orographic effect may maintain light snow showers as the next disturbance approaches Tuesday night. Upper level flow becomes more westerly Tuesday night, with snow levels bumping up a bit but still well below Pass level. A moist airmass will be pushed into the Cascades bringing moderate snow in convergence showers. 

The Long Range: Strong zonal flow will be in place for the Wednesday through Sunday period. Confidence is high in a significant snow event for Stevens Pass and the rest of the Western Cascades for the second half of the week. A warmer airmass will move through on Thursday with snow levels bumping up to 3,000 or so before a strong cold front Friday night. Behind the cold front snow levels lower again and heavy snow continues through the weekend. Details and timing are sure to change, but rough estimates are for 24-36” between Thursday and Saturday morning with continued snow Sunday. 

Precipitation Ending at 4am: Today 24hr water = .5 Snow = 4-6” Tomorrow’s 24hr water = .5-.75 snow = 6-8” Trend and Timing: Light snow during the day Monday, increasing Monday evening and tapering off after midnight. Tuesday should start out with light snow, increasing to moderate Tuesday afternoon and night. 24hr temperature ending at 4 am tomorrow:    Low:  16   High: 26 Snow level: 1500-500’ Trend and Timing: Temperatures will remain steady on the cool side through Tuesday.

24hr Winds (mph) ending at 4 am tomorrow: Base: W 5-10 Ridge Top: WNW 15-25 Trend and Timing:  Winds should move around the the compass between due west and northwest through Tuesday morning with some gusty periods. DV