Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 261056
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
356 AM MST FRI DEC 26 2014

...TRAVEL IMPACTS LIKELY THIS WEEKEND DUE TO SNOW AND BLOWING
SNOW...

.DISCUSSION...

Light snow continues through much of north central Idaho and
western Montana this morning as a shortwave passes. Light snow
accumulations are going to continue through around noon with snow
first to decrease in northwest Montana. Cloud cover will briefly
breakup during the afternoon but will again increase as the next
weather system approaches late this evening.

The next shortwave will begin to produce snow Saturday morning in
northern Idaho and northwest Montana. Locations near and north of
I-90 have a high potential for a moderate to heavy snow storm
Saturday afternoon through Sunday. There is still some question on
where the heaviest snow will fall but confidence is increasing for
widespread travel impacts due to snow accumulations and/or a mix
of gusty winds, moderate snow, and blowing snow. Storm systems
similar to this in the past have produced widespread 5-10 inch
snow accumulations through the valleys of north central Idaho and
northwest Montana, and up to 20 inches in the high terrain. These
similar events increase our confidence for a moderate to high
impact winter storm for north central Idaho, northwest Montana,
and along the Continental Divide, so Winter Storm Watches have
been issued for locations with the highest chance for travel
impacts. One thing to note, although the heaviest snow amounts are
expected generally north of Interstate 90, most all locations in
western Montana and north central Idaho will likely see snow
accumulations by Sunday morning.

Gusty winds with an arctic front on Sunday will increase the
threat  of blowing snow and low visibility from Marias Pass
through Kalispell mainly late morning Sunday through Sunday
afternoon. The gusty winds and lowered visibility will also be
possible from Missoula and east on Highway 200, Highway 12, and
I-90 through Butte and Homestake Pass mainly Sunday afternoon and
evening, so be prepared for poor travel conditions through much of
Sunday.

Cold air will move in behind the front leaving a threat for
dangerous wind chills Sunday night and cold, potentially well
below zero, temperatures through at least the middle of the week.

Another potentially cold and snowy weather system is showing up in
extended model guidance for the end of the week or early next
weekend. This weather system could bring another round of travel
impacts to the Northern Rockies followed by very cold temperatures.

&&

.AVIATION...Snow showers, low ceilings, and periods of visibility
reductions will continue through this morning as a shortwave moves
through the region. Snow will first decrease in northern Idaho and
northwest Montana through this morning with most of the snow to
end around 26/1800z. Sky conditions will improve somewhat today
behind the shortwave but obscured terrain will remain common. The
next weather system will approach this evening so cloud cover will
again increase this evening and tonight with snow to spread
through northern Idaho and northwest Montana during Saturday
morning.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH from Saturday morning through Sunday morning
     Kootenai/Cabinet Region...Lower Clark Fork Region.

     WINTER STORM WATCH from Saturday morning through Monday morning
     Flathead/Mission Valleys...West Glacier Region.

ID...None.
&&

$$



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