Avalanche and Heavy Snow in Idaho, January 11 to 12, 2014

Area Forecast Discussion
National Weather Service Missoula MT
525 AM MST Sat Jan 11 2014

...DAMAGING WINDS TODAY THROUGH EARLY SUNDAY...
...SIGNIFICANT SNOW AND BLOWING SNOW OVER MOUNTAIN PASSES THROUGH
MIDDAY SUNDAY...

.DISCUSSION...

Wind will increase across the Northern Rockies this morning, as a
powerful Pacific storm system approaches the region. Damaging
winds will be present during much of this afternoon and evening,
particularly for high elevations and exposed transportation
corridors, such as along Interstate 90 east of Missoula. Damage to
trees and power lines remains a threat for population centers of
western Montana and north central Idaho. There is a risk of high
profile vehicles becoming imperiled by extreme crosswinds through
early Sunday as well. Significant and prolonged snow and blowing
snow will develop over most area mountain passes this morning.
Travel will be difficult and perhaps near impossible over some of
passes due to snow, blowing snow, and limited visibility.

The majority of the snow and wind is likely to occur from this
morning through midday Sunday, however snow and wind will continue
to be a noticeable travel and life impact, particularly over area
mountain passes all the way through Monday. When all is said and
done, high elevation snow accumulations will measure several feet.
Also, the extreme winds and snow will create snow distributions
that will be a very significant concern for changing snow
avalanche conditions across the Northern Rockies.

By Tuesday, high pressure off the Pacific coast is anticipated to
move inland and over the Northern Rockies. Many valley locations
will develop temperature inversions due to the lack of wind in
wintertime high pressure scenarios. Residual moisture from the
current snow and wind event will likely lead to overnight and
morning freezing fog for northwest and west central Montana
valleys, as well as higher valleys of north central Idaho. Model
guidance depicts a fairly stable high pressure pattern through
Friday.

By Friday, the high pressure ridge shows signs of weakening as the
next Pacific storm cycle approaches the Pacific Northwest coast.
This pattern change will likely destroy the temperature inversions
and bring another round of significant snow to high elevations.

&&

.AVIATION...Very windy conditions across north central Idaho and
western Montana today. Winds will be steadily increasing
throughout the day today with breezy southerly winds and rain
ahead of an approaching cold front. As the front moves through
this afternoon, expect wind gusts to 50mph along and behind the
front. Rain will eventually transition to snow tonight. Mountains
will continue to be obscured throughout the period.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...HIGH WIND WARNING until 5 AM MST Sunday Butte/Blackfoot Region.

     WINTER STORM WARNING until 11 AM MST Sunday Bitterroot/Sapphire
     Mountains.

     HIGH WIND WATCH through late tonight Flathead/Mission Valleys...
     Kootenai/Cabinet Region...Missoula/Bitterroot Valleys.

     WINTER STORM WARNING until 11 AM MST Sunday Lower Clark Fork
     Region.

     WINTER STORM WARNING until 11 AM MST Sunday Potomac/Seeley Lake
     Region...West Glacier Region.

ID...WINTER STORM WARNING until 11 AM MST Sunday Eastern Lemhi
     County...Western Lemhi County.

     HIGH WIND WARNING until 4 AM PST Sunday for the Camas Prairie...
     Grangeville and Highway 95 IN THE Lower Hells Canyon/Salmon
     River Region...Orofino/Grangeville Region.

     WINTER STORM WARNING until 10 AM PST Sunday Northern Clearwater
     Mountains...Southern Clearwater Mountains.

&&

Zumpfe
Aviation...Kino

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