Snow Squall Warning 7, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
229 PM MDT Mon Apr 4 2022

.DISCUSSION...

Damaging winds and intense snow showers continue as the main
impacts into Tuesday:

Damaging Winds: A cold front and mountain wave enhanced winds will
continue to bring a high potential for gusts in excess of 50 mph
for much of the Northern Rockies well into this evening. Impacts
include tree damage, unsecured objects could be thrown, downed
power lines, and dangerous crosswind for high profile vehicles.
Although it will remain windy late tonight and on Tuesday for the
entire region, the main threat for damaging winds will be through
this evening. Exceptions include the Missoula/Bitterroot valleys,
the Salmon vicinity, and Southwest Montana. For the
Missoula/Bitterroot valleys and the Salmon vicinity, there
continues to be a concern for re-intensification of winds with
passing snow showers later tonight into early Tuesday. Meanwhile,
very strong winds are expected to continue on Tuesday in
Southwest Montana.

Snow: Behind the cold front this afternoon there will be
transition to an unstable atmosphere with periodic heavy snow
showers/snow squalls as snow levels drop to valley floors. The
primary concern is for passes where road temperatures will be cold
enough for periodic accumulations and slick roads. Southwest
Montana is also a concern with the cold front late this afternoon
as high-res models show a squall line developing with sudden ice
and snow accumulations, even in the valleys. Additionally, there
is a potential for brief accumulations in the lower valleys area
wide, mainly on Tuesday morning. Travelers should be ready for
changeable road conditions and sudden reduced visibility through
Tuesday evening.

After a cold start to Wednesday morning, a few snow showers linger
through the day, especially across Northwest Montana but overall
it will be a much drier day with seasonable daytime temperatures.

Although a warming and drying trend is still anticipated for
Thursday and Friday under high pressure ridging, the window is
getting narrower. By Friday afternoon, scattered showers are
possible once again.

Forecast model ensemble continue to agree on a large, cold trough
of low pressure across the Northern Rockies this weekend through
early next week. Temperatures will once again be well below normal
with periods of showers. This pattern certainly leaves open the
potential for closed lows to develop which would lead to
widespread precipitation, something to watch closely. Snow levels
will be at valley floors much of the time. In addition, cold
morning low temperatures could be particularly hard on any
sensitive annuals that are left outside.

&&

.AVIATION...The cold front and strong upper level jet will
continue to move through the region. Southerly winds will shift to
westerly and become strong with around a 90 percent probability of
widespread wind gusts greater than 41 knots. KGPI, KMSO, KBTM, and
KSMN have a 50 percent probability of higher wind gusts over 48
knots by 05/0600z. Strong mountain wave winds are also expected on
the east side of north-south oriented mountain ranges, such as
the Bitterroot Mountains, where there is around a 70 percent
probability of greater than 56 knot winds. Area webcams show
mountain passes obscured in snow, and snow levels will lower
behind the cold front. Reduced visibility in snow showers is
expected even to valley floors, but accumulations will mostly be
limited to higher valleys and in the mountains. A tight westerly
pressure gradient will remain over central Idaho and western
Montana through Tuesday resulting in continued gusty winds. Snow
showers will also reduce visibility on Tuesday and will enhance
wind gusts.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning until 6 PM MDT Tuesday Butte/Blackfoot Region.

     Winter Weather Advisory until noon MDT Tuesday Butte/Blackfoot
     Region.

     Winter Weather Advisory until noon MDT Tuesday
     Bitterroot/Sapphire Mountains.

     High Wind Warning until 6 AM MDT Tuesday Bitterroot/Sapphire
     Mountains.

     High Wind Warning until 6 AM MDT Tuesday Missoula/Bitterroot
     Valleys.

     High Wind Warning until midnight MDT tonight Lower Clark Fork
     Region.

     Winter Weather Advisory until noon MDT Tuesday Lower Clark Fork
     Region.

     High Wind Warning until midnight MDT tonight Flathead/Mission
     Valleys.

     High Wind Warning until 6 AM MDT Tuesday West Glacier Region.

     Winter Weather Advisory until noon MDT Tuesday West Glacier
     Region.

     High Wind Warning until midnight MDT tonight Kootenai/Cabinet
     Region.

     High Wind Warning until midnight MDT tonight Potomac/Seeley Lake
     Region.

ID...High Wind Warning until midnight MDT tonight Eastern Lemhi
     County.

     Winter Weather Advisory until noon MDT Tuesday Eastern Lemhi
     County.

     High Wind Warning until 11 PM PDT this evening Northern
     Clearwater Mountains.

     Winter Weather Advisory until 11 AM PDT Tuesday Southern
     Clearwater Mountains.

     High Wind Warning until midnight MDT tonight Western Lemhi
     County.

     High Wind Warning until 11 PM PDT this evening
     Orofino/Grangeville Region.

     High Wind Warning until 11 PM PDT this evening Southern
     Clearwater Mountains.

&&

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