February 27, 2018

MOUNTAIN WEATHER FORECAST - Update


Time and Day:  1000 Tuesday  

No significant changes to this mornings forecast.   The timing and intensity for tomorrow' storm is still question.  

The Snapshot: Light snow, breezy with slightly warmer temperatures will be the weather pattern today and tomorrow.   A drying trend begins on Thursday with the weekend following suit.

The Science

Current Observations:  The satellite image has light snow falling in the mountains and a band of rain moving into the coastal region.  The temperature profile is 25 base / 19 ridges.   The barometer is 1013mb’s and falling and the winds are westerly and gusting 5-15mph.   

The Forecast:   A low pressure system will slowly slide down the Canadian Coast today.  This will push moisture into the region with light snow for Stevens Pass for most of the day.  

There is a weak triple point frontal associated with this low pressure system.  The models disagree on the impact of this system to Stevens Pass. The GFS model has the front stalling and weakening while the European model has it being a bit more potent.  As with previous triple point storms, we can expect the freezing levels to rise and fall with the passing of the fronts.  The flow also shifts easterly tomorrow which will help hold temperatures in check, but cancel out the westerly orographics (no convergence).   

The Long Range:  A prolonged dry period will begin on Thursday as a high pressure cell slowly drifts into the region. 

24hr values daily 4am to 4am.
Precipitation:
Today 24hr
water: .25-.5  snow: 4-6

Tomorrow’s 24hr
water: .25-.5  snow: 4-6

Trend and Timing:
Light snow will begin today and continue through the night.  There will be a lull in the snow tomorrow morning with light snow beginning again tomorrow afternoon.


Temperature:
Low: 18    High: 28
Freezing level: 3500’ – 2500’- 3500’.  

Trend and Timing:   
The freezing levels will peak near 3500’ today and then fall tonight and then rise back up to +-3500’ tomorrow.

 
Winds
Base: 5-10 W
Ridge Top: 10-15 W

Trend and Timing:
Westerly flow will strengthen today with east flow developing tomorrow.



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