MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Thursday, December 19, 2019, 0730

Current Observations:

24hr Precipitation:      .26”SWE, 6” of snow

Temperature profile:     22 base, 26 ridge

Pass level winds:            light westerly

Barometer:                 1008mbs’ and rising slightly

Sky:                             broken passing clouds

Radar:        Spotty showers in the mountains and the next band of moisture still a ways offshore.

The Forecast:  Light snow showers today with heavy snow turning to rain tonight.  Mixed rain and snow shower are expected tomorrow and Saturday.

Long Range:  The show comes to an end late Saturday night with remnant snow showers extending into Sunday.  Another series of storms is setting up the holiday week – with snow and favorable temperatures.  

  

The Science:   The well-advertised atmospheric river, is in route with the leading warm front entering the southern cascades and slowly tracking NE.  Strong, warm SW flow with a ton of moisture will crash into the Cascades tonight.   Snow turning to rain and then shifting back to mixed rain and snow will likely be the outcome over the next 24hrs. Fickle freezing levels (+-4500’) with heavy precipitation will be the game through Saturday.  

Winds will also be a player as pressure gradient tighten overnight.  Models have 50+ knot, 6000’ SW winds kicking in late tonight.  Usually, Stevens Pass is fairly protected from SW flow, so we will see how the winds play out.    

Confidence:  Good.

Values from 4am today through 4am tomorrow.

Precipitation: Today 24hr water: 1-1.5” snow:  5-8”  Tomorrow’s 24hr water:  1.5  snow: 6-8” Trend and Timing:  Snow begins after 4pm today with snow changing to rain around midnight.  Mixed rain and snow can be expected tomorrow and Saturday.

Temperature: Low:22    High: 36 Freezing level: 2500’ – 5500’ Trend and Timing:    Freezing levels will slowly rise today.  Freezing levels will peak +5000’ around midnight tonight.   Freezing levels will fall back to 4500’ by tomorrow with temperatures near freezing through Saturday.

Winds Base: 0-10 ESE shifting SW Ridge Top:   5-15 SW  strong gusts Trend and Timing: Weak east flow will slowly be taken over by SW flow aloft through the day. Strong SW winds (6000’ – 40 knots) will be possible tomorrow morning.