January 8, 2017

MOUNTAIN WEATHER FORECAST

Time and Day: 0730 Sunday

The Snapshot:  Increasing snow tonight with a spike in temperatures,  snow showers, and cooler temperatures lead into tomorrow.   

Freezing rain warning for the roads, careful driving out there.

The Science:  The Stevens Pass mountain itself shouldn’t see much if any rain; the freezing levels are expected to briefly spike to 4000’ tonight.  Cold air trapped in the eastern basin with warm air aloft is surely a formula for the rain freezing on the cold surfaces.

A warm front associated with a triple-front frontal system, will bring a short period of snow and a brief spike in the temperatures tonight.  The following cold front will usher in cold air and diminish the precipitation in its wake. Therefore expect light snow today with moderate snow this evening, diminishing overnight.  East winds will increase ahead of the warm front before they shift SW with the passing of the cold front.  A weak high pressure ridge in the mix will produce some clearing between snow showers tomorrow.   

The Long Range:   The low-pressure system stationed offshore will continue to spin bands of snow into the Cascade Mountains through the middle of the week.  The moisture then drifts south with Washington state trending dry for the second half of the week.  

Precipitation Ending at 4am:

Today 24hr water = <.5  Snow =  3-5

Tomorrow’s 24hr water = lt.25 snow = 1-3

Trend and Timing:
Light snow today with a moderate period of snow between 4 pm and midnight.  Snow quickly tapers off early tomorrow morning.


24hr temperature ending at 4 am tomorrow: 
Low: 15    High: 28
Freezing level: 500-3500’

Trend and Timing:   
Temperatures will rise today with freezing levels briefly spiking around 4000’ this evening – between 7 pm and 10 pm.  Freezing levels fall back to +-2500’ overnight.

 
24hr Winds (mph) ending at 4 am tomorrow:
Base:  5-15 E shifting WSW
Ridge Top: 10-15 E shifting SW

Trend and Timing:
Easterly wind will increase today and shift WSW overnight. 




jM

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