Snow Avalanche Guidance
Issued by NWS Missoula, MT

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000
FWUS45 KMSO 191109
SAGMSO

Backcountry Forecast for western Montana and north central Idaho
National Weather Service Missoula MT
409 AM MST FRI DEC 19 2014

DISCUSSION:

The next in a series of weak storm systems will traverse the
Northern Rockies from the west through today. Snow amounts for
mountain pass elevations and higher will be limited to 6 inches or
less for most locations. The relatively warm nature of the system
today will make for low snow ratios.

A significant surge of subtropical moisture is expected late
Saturday through Sunday, pushing snow levels up to 6000 feet for
a time. Even for the high elevations where precipitation remains
entirely snow, low snow ratios will be common. Ridgetop winds
will also be on the increase, redistributing some snow to east
facing slopes. Snow levels will gradually return back to 4000 feet
and lower by late Sunday night.

Winds aloft will become northwesterly throughout the coming week,
allowing for colder air and relatively high snow ratios to exist.
Snow will not be continuous, however fairly consistent light
accumulations each day. Weather models continue to suggest a
significant change in the Thursday/Friday time frame, when a blast
of arctic air arrives over the Northern Rockies. Significant
snowfall appears to be far south and east of the region, however.

For the latest information on watches, warnings and advisories, go
to weather.gov/missoula.

&&
Elevations above 4,000 FT:

                      TODAY        TONIGHT      SAT
Cloud Cover           85%          75%          75%
Hi/Lo Temps           30 to 36     20 to 28     28 to 35
Winds(mph)            SW 10G23     SW 12G29     SW  9G23
Precip Chc            80           60           50
Precip Type           snow         snow         snow
Liquid Amt            0.14         0.07         0.05
Snow Ratio(SLR)       14:1         17:1         16:1
Snow Amt(in)          2-4          1-2          1-2

Snow Level            3000         4000         2500

$$


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