February 23, 2020

MOUNTAIN WEATHER FORECAST


Stevens Pass Mountain Weather Forecast
Date: Monday, February 23, 2020


Current Observations:
24hr Precipitation: 1” snow / .07” SWE                    
Temperature profile:  28 base / 26 upper mtn
Pass level winds: West  10-15              
Barometer: 1006 and falling rapidly              
Sky: Obscured, snowing heavily                                 
Radar: Widespread precipitation across Western WA


The Forecast: Heavy snow and windy today with cooling overnight. Snow showers becoming light and ending tomorrow.

The Science: A deep low pressure system riding along a strong jet streak is making landfall in Washington this morning. The barometer is falling rapidly indicating the approach of the low, and temperatures have bumped up a notch as the warm sector rides over us. The cold front is not far behind and freezing levels will remain well below pass level. The winds have increased as the front approaches and should remain moderate to strong and gusty all day. A strong burst of low level post-frontal westerly winds will maintain orographic showers this afternoon and tonight with convergence zones likely setting up in the Central Cascades. If that all wasn’t enough, temperature lapse rates in the middle layers of the atmosphere seem to support convective build up with thunder possible as well. NW upper level flow will turn more northerly Monday with snow turning to showers Monday morning and winds abating. Temperatures should remain cool Monday.

Long Range: High pressure builds Tuesday for a quiet day. Light snow is possible Wednesday with zonal flow bringing a weak system to our north.

Confidence: Good for general setup, poor for exact upper end snow amounts.

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water: 1.5  snow: 14-18”

Tomorrow’s 24hr
water:  .25 snow: 4”

Trend and Timing:
Moderate to heavy snow today, with heavy snow continuing tonight, becoming showery Monday.

Temperature:
Low: 20   High: 28
Freezing level: 3000’ – 1000’

Trend and Timing:   
Rapid cooling today and tonight.
 
Winds
Base: W 10-20
Ridge Top: W 30-40 with higher gusts possible

Trend and Timing:
Gusty winds have begun this morning and should continue most of the day and tonight before dying down Monday morning.

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