February 18, 2019

MOUNTAIN WEATHER FORECAST


Stevens Pass Mountain Weather Forecast
Day and Time:   Monday 0700

A potential powder day is in the works for Wednesday.

Current Observations:
24hr Precipitation:  0
Temperature profile: 22 base, 17 ridge
Pass level winds: light, northerly
Barometer: 1020mb’s and rising
Sky:  partly cloudy
Radar: most of the State is completely dry with precipitation echo’s popping up just offshore.   

The Forecast:  Partly sunny today with cool temperatures.  Snow arrives tomorrow. 

Long Range: Snow showers are expected to linger into Wednesday.  Thursday will be a dry interim day with a similar NW oriented winter storm expected on Friday.
  
The Science: A weak frontal boundary is moving into the intermountain west this morning. This will mark the start of a shift in zonal flow for the PNW.  NW flow with an approaching cold front will bring a more typical winter storm to the Cascade Mountains tomorrow. A period of good orographic with a potential Puget Sound Convergence Zone development is possible.  The freezing levels will bump up a bit as the front approaches but fall in its wake.      

The atmosphere will remain unstable through Wednesday as the low pressure system drifts south over the region.  Cool easterly flow with a weak high pressure ridge will produce a dry day with partial clearing on Thursday.

Forecast confidence:  Good for the next 24hrs.  Tomorrow’s system is still under development, so 36-48hrs confidence is fair.   

Values from 4am today through
 4am tomorrow.
Precipitation:
Today 24hr
water: lt .10  snow: trace

Tomorrow’s 24hr
water: .75  snow: 6-8

Trend and Timing:
Mostly dry today with snow arriving after 10am tomorrow.


Temperature:
Low: 18   High: 26
Freezing level: +- 500’

Trend and Timing:   
Freezing levels will dip below 1000’ today with some daytime temperature recovery.   Freezing levels bump up to +-2000’ tomorrow afternoon.

 
Winds
Base: 0-10 W
Ridge Top: 5-10 W

Trend and Timing:
Winds will shift to westerly this morning with the flow pattern remaining westerly through tomorrow.


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0800 Start Tues Jan 20th, no ABS