Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 201110
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
410 AM MST Sat Jan 20 2018

.DISCUSSION...
Scattered snow showers continue to bring brief shots of snowfall
to north-central Idaho and west-central/northwest Montana this
morning. This pattern is likely for the rest of today, with
precipitation emphasis over the terrain in these locations. A weak
shortwave tonight may allow additional snowfall through west-
central Montana overnight, but accumulations are anticipated to be
minimal.

Shower coverage will start to taper off throughout the day Sunday
with brief high pressure. Then, widespread light snow returns
across the area late Sunday into Monday, and a few inches are
currently forecast over mountain passes with periods of slick
travel conditions. Light snow accumulations are also possible in
the valleys of north-central Idaho and western Montana. Short-
range models continue to suggest a period of a "shadowing effect"
Monday morning for valleys such as the Flathead/Mission,
Missoula/Bitterroot, and southwest mountain valleys as winds
temporarily transition westerly aloft, meaning that precipitation
will have a harder time amounting to much Monday morning. However,
expect scattered snow showers to linger in the area throughout
the day Monday.

There will be yet another brief break in the snowfall on Tuesday
as weak high pressure traverses the area. In fact, models now
suggest this period of warmer and dry weather could extend into
Wednesday for much of Idaho and western Montana in response to a
slower trough digging into the Pacific Northwest. However,
Wednesday night/Thursday morning a cold front will sweep across
the area and lead to snow for most elevations. The main upper
level trough will escort several waves of energy over the
Northern Rockies Thursday night through Friday night leading to
periods of snow showers. These showers could be somewhat
organized and at times, quite strong. While the areas most
susceptible to the strongest showers remain a bit too challenging
to forecast with high confidence, at this time the Clearwater and
Southern Bitterroot Mountains along with attendant valleys appear
most favored in the model data.

It does look like a decreasing trend in shower activity is
possible again on Friday which could possibly extend into next
Saturday. Beyond that the model solutions become highly varied,
though the overall trends do lean towards yet another active
period (colder with snow) developing to end the month.

&&

.AVIATION...A few scattered snow showers will persist in the
region today, especially for the terrain of northwest/west-central
MT and north-central ID. These showers will remain in the
vicinity of KMSO and KGPI the next 24 hours, potentially bringing
light snow to these terminals before showers decrease in coverage
by Sunday morning. A few low clouds and brief visibility
reductions will be possible with showers, but accumulations are
expected to be minimal.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$



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