January 4, 2018

MOUNTAIN WEATHER FORECAST

Time and Day:  0700 Thursday

The Snapshot:  Temperatures will increase today with light mixed rain and snow showers expected tonight and tomorrow.  A short dose of good snow is shaping up for early Saturday morning.  The rest of the weekend will be dry with some potential sunshine.  

There may be a freezing rain (ice) component tonight – so be careful out there. 

Weather lesson for the day:  Freezing rain is not rain that freezes as it falls, but rain that lands on very cold surfaces and freezes to form ice on that surface.  J

The Science

Current Observations: Clouds are starting to roll in with temperatures in the 20’s.  The barometer is currently sitting at 1017mb as slowly descending.  The winds are easterly 5-10mph.  Satellite images have most of the incoming activity currently to the south of Stevens Pass.

The Forecast:  A low-pressure trough approaching the west coast will push out this stagnate air mass today.  This will open the door for warm moist southerly flow to enter the region.   The big question is how the warm air aloft mixes with the leftover cold air and how the precipitation plays into that.  There is not a huge amount of moisture with the first push so expect just light mixed snow/rain with a potential of freezing rain through tomorrow.

Cold front swings in early Saturday morning with a short, intense shot of snow possible.  The timing for this is currently between midnight Friday and 10 am Saturday.  That timing will be fined tuned later today or tomorrow.   

The Long Range:  The snow ends mid-morning on Saturday with the weekend trending dry and clear.   Another system lifts up from the south on Monday.     

24hr Precipitation ending at 4 a.m:
Today 24hr water: .25  snow: 1-2”
Tomorrow’s 24hr water:.75+  snow: 6-8”

Trend and Timing:
Light mixed rain and snow start this afternoon with intermittent showers through the day tomorrow.


24hr temperature ending at 4 a.m: 
Low: 22    High: 28
Freezing level: 5000’

Trend and Timing:   
Freezing levels will rise to 5000’ tonight and hover around that elevation into the early morning hours of Saturday.  East flow will help hold surface temperature near freezing through that period as well.  

 
24hr Winds (mph) ending at 4 a.m:
Base: 0-5 E
Ridge Top: 5-10 E

Trend and Timing:
East flow will continue through tomorrow. 


jM

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