November 30, 2015

MOUNTAIN WEATHER FORECAST

Time and Day: 1100

The Snapshot:  Brr, single digit temperatures with a stiff east wind today.  High clouds with a few snow flurries tonight, snow tomorrow night, mixed rain and snow Wednesday - Saturday.  

The Science:  The high-pressure ridge that has dominated our weather is beginning to drift into the intermountain west of Idaho and Montana.   This will allow a series of complex storms to slide up along the western slopes of the Cascades starting tomorrow night and continuing through the upcoming weekend. 

Stevens Pass will be the on the front lines of a battle between the approaching warm, moist, and unstable air mass and the cold, dry conditions east of the mountains.  The first front arrives tomorrow night with snow likely into early Wednesday morning.  The next, slightly warmer system enters the mountains Wednesday afternoon with mixed rain and snow falling into Thursday morning.   If the temperatures cooperate, we could squeeze a foot or more of snow out of these storms. 

Storm totals calculations:
Tuesday 4 pm – Wednesday 4 pm  .25 -.5” water  2-5” of snow
Wednesday 4m – Thursday 4 pm   1” of water  4-12” of snow (east flow dependent)
Friday – Snow likely – amounts still in question.

Long Range:  Models are having difficulties nailing down Friday and beyond.  There is potential to have a good snow event if and when a low-pressure trough develops off shore on Friday/Saturday.  Stay tuned as those details develop.   


Precipitation ending at 4 am:
Today’s 24hr Water = .10   Snow =  Trace

Tomorrow’s 24hr Water = .25   Snow = 2-4 

Trend and Timing:
Mostly dry with some very light snow through 4 pm tomorrow.  Snow expected late tomorrow night into the early morning hours of Wednesday.


24hr temperature ending at 4 am tomorrow: 
Low:  12  High:  24
Freezing level: 2000’ - 4000.'

Trends and Timing:
East flow will hold surface temperatures well below freezing through tomorrow.   The temperature inversion will continue with rising freezing levels along the western slopes.

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

Trend and Timing:
Easterly winds will continue through early Wednesday morning.



JM

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