563
FXUS65 KMSO 202034
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
134 PM MST Thu Nov 20 2025

.DISCUSSION...

KEY MESSAGES:

 - Fog Redevelopment: Where cloud cover is able to clear, valley
   fog is expected to reform tonight into Friday morning.

 - Mild Weekend: Confidence remains high for unseasonably warm
   temperatures this weekend (10-15 degrees above normal).

 - Strong Cold Front Monday: A vigorous system arrives early next
   week bringing widespread gusty winds, mountain snow, and a
   return to seasonal temperatures.

Morning fog and low stratus have largely eroded, giving way to
partly cloudy skies and mild afternoon conditions. The overarching
weather pattern remains driven by a high-pressure ridge that will
dominate through the weekend. However, the partly cloudy skies
and light winds tonight will set the stage for radiational cooling
and development of fog and/or low cloud cover.

Saturday and Sunday will feature highs in the upper 40s to near
50 degrees. The 12Z model suite continues to show decreasing
precipitation chances this weekend. Given the strength of the
ridge, we are leaning toward the drier solution for the valleys,
with any light rain showers likely confined to the immediate ID/MT
border and Glacier Park region.

Attention remains fixed on the cold front slated for Monday.
Forecast confidence is increasing regarding the strength of this
system. The pressure gradient aligns for strong westerly winds.
Gusts of 30-45 mph are likely in the valleys, with gusts exceeding
55 mph possible along the Continental Divide (near MacDonald
Pass) and favored wind-prone areas like Anaconda. Snow levels will
crash from 6000ft to valley floors by Tuesday morning. Travelers
over Lookout, Lolo, and Marias Passes on Monday afternoon/evening
should prepare for winter driving conditions, with 2-5 inches of
accumulation possible.

There is now a trend toward increased shower chances on Wednesday
and Thursday in the latest ensemble guidance. Temperatures will
be noticeably cooler (highs in the 30s), which increases the
chances for light valley snow. Travelers should stay tuned as
mountain and valley snow showers are possible in the post-frontal
northwest flow for the second half of the week.

&&

.AVIATION...Areas of low clouds and valley stratus remains
entrenched across much of the Northern Rockies airspace this
afternoon. Recent satellite observations highlight areas of
clearing along the ID/MT border in northwest MT and along the
divide in southwest MT. The region will stay under the influence
of a ridge of high pressure into Friday morning, with moisture
remaining trapped within the boundary layer. This set up increases
chances for the redevelopment/expansion of stratus and valley fog
overnight. Recent trends suggest widespread stratus, with a greater
risk for fog in areas that experienced clearing today.

&&

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

$$