Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 222122

Area Forecast Discussion
National Weather Service Missoula MT
222 PM MST Sun Jan 22 2017

.DISCUSSION...A weather disturbance is currently moving through
central Idaho this afternoon, and will continue to shift into
western Montana this evening. Most locations above 2000 feet will
see snow this evening into the overnight hours, though the best
accumulations are expected across northwest Montana, generally
north of the Missoula valley. The combination of snow and liquid
refreezing on roadways tonight will make for slick travel
conditions, especially during the Monday morning commute. Numerous
winter weather advisories have been issued through tomorrow

Precipitation will largely decrease in coverage and become more
showery by Monday morning. Forecast models indicate there may be
enough dry air across central Idaho and west central Montana to
have some clearing skies near sunrise. This may allow for areas of
fog to form once again, possibly even becoming dense at times. In
addition to low visibility, freezing fog will certainly not help
the already slick road conditions.

Northwesterly flow will become the dominant pattern Tuesday
through the end of the week. Moisture seems to be abundant enough
during this time period to produce steady snowfall in higher
terrain, adding a couple of fresh inches of snow to highways
that cross over Lookout, Marias, and Lolo passes. Periods of
valley snow showers will also be possible, though will be most
prominent on Tuesday and Wednesday.

By Thursday night, most of the moisture diminishes and will allow
for clearer skies and dropping valley temps. Friday morning could
be quite cold, with values in the single digits for valleys along
the Divide and into southwest and west central Montana. Cold
temperatures may last through Sunday before the next chance for
precipitation enters the picture.


.AVIATION...The next wave of snowfall has begun to move through
central Idaho this afternoon, and will shift into west-central
Montana early this evening and into northwest Montana tonight. All
airfields will see periods of snow, though KMSO and KGPI will
likely see the biggest impacts due to lowered ceiling and
visibility. The most likely timing for precipitation at area
terminals follows:

KSMN: 22/2200z-23/0300z
KBTM: 23/0000z-23/0400z
KMSO: 23/0200z-23/0600z
KGPI: 23/0500z-23/1200z

Showers will likely linger through the morning hours across
northwest Montana and near the Continental Divide, though
intensity of precipitation will be on the decrease. Another
aviation concern come Monday morning will be for another round of
freezing fog, which could become locally dense. It looks as though
fog may form around sunrise as this is when we may start seeing
some breaks in the clouds. Airfield KMSO stands the best chance
of seeing some visibility and ceiling reductions due to fog.


MT...Winter Weather Advisory from 5 PM this afternoon to 11 AM MST
     Monday Missoula/Bitterroot Valleys.

     Winter Weather Advisory from 5 PM this afternoon to 11 AM MST
     Monday Lower Clark Fork Region...Potomac/Seeley Lake Region.

     Winter Weather Advisory from 8 PM this evening to 11 AM MST
     Monday Flathead/Mission Valleys...Kootenai/Cabinet Region...
     West Glacier Region.

ID...Winter Weather Advisory until 4 AM PST Monday ABOVE 2500 FEET
     for the Northern Clearwater Mountains...Southern Clearwater


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