MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Date: Monday, December 30, 2019

Current Observations:

24hr Precipitation: 0

Temperature profile: 22 base / 31 mid mtn

Pass level winds: Variable, light

Barometer: 1020 steady

Sky:  Partly cloudy, light snow flurries

Radar: There’s a band of light rain in the northern interior, and spotty snow flurries along the crest.

The Forecast: Increasing clouds with a chance of flurries today, stormy with moderate snow then rain/snow mix Tuesday.

The Science: A weak warm front is riding over the top of an east-west oriented high pressure ridge this morning, bringing light rain to the Puget Sound area and isolated snow flurries in the Cascades. The main affect at Stevens Pass will be increasing upper cloud cover and the end of the inversion conditions we’ve had the past few days. A more uniform temperature profile should set up as the Pass level winds have already switched to westerly.

Tonight the ridge should flatten out as a westerly jet begins to take aim at the PNW. The first in a series of vigorous storms will move in Tuesday morning. Freezing levels are favorable for snow to start the event, and moderate accumulations can be expected during the day tomorrow. A switch to rain looks likely mid-afternoon as the warm sector arrives and pushes freezing levels above 5,000’. The trailing cold front should sweep through overnight on Tuesday, dropping freezing levels below pass level again with continued precip (snow).  

Long Range: Light to moderate snow expected Wednesday with convergence zones popping up, making for varying snowfall amounts. Another, colder storm arrives Thursday with favorable snow accumulations for Stevens Pass. Active weather continues through the weekend with lowering freezing levels.

Confidence: Poor starting Tuesday morning for exact snowfall amounts and timing of precipitation-type changes. 

Values from 4am today through 4am tomorrow.

Precipitation: Today 24hr water: .10 snow: Trace-2” Tomorrow’s 24hr water: 1-1.5”  snow: 6-8” Trend and Timing: Mostly dry Monday with precipitation beginning as snow Tuesday morning, switching to rain in the afternoon, and back to snow early Wednesday morning.

Temperature: Low: 21   High: 33 Freezing level: 4000’ Trend and Timing:    As the inversion scours out this morning, the temp profile should become more uniform, steady temperatures thru Tuesday morning.

Winds Base: West 5-10 Ridge Top: WSW 10-15 Trend and Timing: Light winds increasing to moderate Monday evening.