December 17, 2015

MOUNTAIN WEATHER FORECAST

Time and Day: 0630 Thursday

The Snapshot:  Lot of snow today with warming tonight. Intermittent snow showers will persist through Saturday with another organized storm on Sunday.

The Science: The approaching warm front passed over the Washington coastline around 3 am this morning and is slowly moving east.  Snow will intensify through the day as the front moves into and eventually east of the mountains during the next 12-16 hrs.   Strong easterly flow will keep temperatures below freezing for most of the day but begin to weaken this evening.  Once the front moves east of the mountains freezing levels briefly spike to 4500’ – the timing and duration of this is still in question but appears to happen early tomorrow morning (2 am -7 am).    

A cold front with cool NW flow in tow will drop the freezing level to +- 2000’ tomorrow and deminish the precipitation to light intermittent snow showers.  Not much new snow accumulation is expected from noon tomorrow through Saturday.

Long Range:   This winter storm cycle will continue with the next organized system on Sunday.   More storms are lining up to keep the snow machine pumping into the PNW Mountains through most of next week.  

Precipitation ending at 4 am:
Today’s 24hr Water = 1.25   Snow = 12-16

Tomorrow’s 24hr Water = .25-.5   Snow =  3-5

Trend and Timing:
Heavy snow today.  Snow changes to shower tomorrow morning.  Watch for a brief mixed rain and snow period between midnight and 7 am tomorrow.   Snow changes to intermittent light showers tomorrow afternoon.


24hr temperature ending at 4 am tomorrow: 
Low: 22 High: 32
Freezing level: 2000’ – 4500’ – 2000.'

Trends and Timing:
Temperatures will slowly rise tonight with freezing levels briefly peaking around 4500’ after after midnight or so.  Freezing levels fall below 2500'.

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

Trend and Timing:
East flow should persist into early tomorrow morning.  Wind shift SW then NW tomorrow.



jM

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