MOUNTAIN WEATHER FORECAST

  Stevens Pass Mountain Weather Forecast

Monday, 12/9/2019, 0800a

Current Observations:

24hr Precipitation:      .06 SWE,  trace of snow (snow makers are producing this morning)

Temperature profile:    28 base,  30 ridge

Pass level winds:          calm

Barometer:                  1019mb’s and slowly falling

Sky:                             clear

Radar:   Mostly clear and dry for Washington State this morning.  A cold front with an advancing band of moisture is +100 miles offshore and tracking ENE.

The Forecast:  Mostly dry, warm and clear today with increasing clouds tonight.  Light mixed rain and snow showers can be anticipated tomorrow afternoon.

Long Range:  The next good potential of snow starts Wednesday night and last through early Friday morning.  See below for early storm totals.  

  

The Science:  Warm air advection creeping up the western slopes has created a temperature inversion this morning.  Daytime temperatures will peak near 40 today as the warm air continues to invade. 

The high pressure ridge over the PNW is expected to weaken of the next 24hrs.  This will open the door for a few disturbances to pass through the region. 

The first system is expected to arrive tomorrow afternoon. There isn’t a lot of energy associated with this first storm so we should expect much snow accumulation. Temperatures will be near freezing so mixed rain and snow is likely.

A stronger system will drive in late Wednesday night for some potential snow accumulation.   Storm totals from Wednesday 4pm through Friday 4am, as of now are:  .75-1” SWE, 8-12” of snow.  Snow showers persist into Friday with the weekend trending dry under building high pressure.  Freezing levels will be +-4000’ through this event so hopefully snow will be the form of choice.  

As usual, an update will be posted if there is any changes to this forecast over the next 24hrs.

Confidence:  Good short term, fair for the long range.

Values from 4am today through 4am tomorrow.

Precipitation: Today 24hr water: 0 snow: 0 Tomorrow’s 24hr water: .25  snow: 1 lower mountain, 1-3 upper ridge. Trend and Timing: The next 24+ hours will be dry with moisture arriving tomorrow afternoon.

Temperature: Low: 30   High: 40 Freezing level: 4000’- 5500’ Trend and Timing:    Freezing levels will push up to 5500’ or higher today and then slowly fall tomorrow.

Winds Base: 0-5 E Ridge Top: 0-5 E Trend and Timing: Very light winds today with increasing WSW flow tomorrow afternoon.