December 12, 2015

MOUNTAIN WEATHER FORECAST

Time and Day:  0600 Saturday

The Snapshot:  Mr. Winter storm is on track to bring snow to Stevens Pass for the rest of the weekend.  A high wind advisory will be in effect tonight and tomorrow as well.

The Science:  Snow should start falling in the mountains this morning with the main front hitting the western slopes around noon or so today. This system is a triple point storm with a warm front today followed by a cold front tonight. 

Once the cold front moves through, strong westerly winds will kick in, and the snow will turn to showers.  However, strong westerly flow will set up the Puget Sound Convergence Zone allowing the snow showers to be persistent and intense.  NW flow with an unstable cooling atmosphere will keep snow falling through early Monday morning.

Long Range:  Snow will end on Monday as high pressure begins to build off the NW coast.  Cold air flowing in from the north will drop temperatures into the teens early next week.  The second half of next week will see a return to active weather. 

Precipitation ending at 4 am:
Today’s 24hr Water = +-.75   Snow = 8-10

Tomorrow’s 24hr Water = +- .75   Snow =  6-8

Trend and Timing:
Snow starts around noon today and will continue through the night.  Convergence conditions may push snow totals up with the most intensity happening late tonight.


24hr temperature ending at 4 am tomorrow: 
Low: 24 High: 30
Freezing level: +3500’ – 3000’

Trends and Timing:
Freezing levels will remain below Pass level for this storm cycle.  Watch for a quick spike in temperatures as the warm front approaches this morning.  Temperatures will fall in the wake of the cold front tonight.

 
24hr Winds (mph) ending at 4 am tomorrow:
Base:  0-5 E shifting W
Ridge Top:  5-10 E Shifting W  strengthening

Trend and Timing:
East flow will shift westerly with the passing of the cold front tonight.  Strong westerly winds can be expected through tonight and tomorrow.



JM

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