556
FXUS65 KMSO 210940
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
240 AM MST Fri Nov 21 2025

.DISCUSSION...

KEY MESSAGES:

- Mild Weekend: continued unseasonably warm temperatures (about
   10 degrees above average) are expected this weekend

- Monday Cold Front: A sharp change in weather arrives Monday,
   bringing strong winds, cooler temperatures, and snow to
   mountain passes.

- Snow to valley floors Wednesday to Thanksgiving Day

High pressure off the West Coast will keep the polar jet north of
the border well into the weekend. Mostly dry westerly flow will
persist over the Northern Rockies during this time, resulting in
morning valley fog and mild temperatures. Daytime high
temperatures will stay about 10 degrees above normal through
Sunday. Limited moisture arriving via the jet stream to the north
will keep clouds and some outside chances (20-30 percent) for
precipitation in the forecast for today in northwest Montana along
the Idaho border. Precipitation has been trending drier for
Saturday, and has all but disappeared from this edition of the
forecast. Sunday will remain mild as a trough of low pressure
moves onshore over the Pacific Northwest, pulling the jet south
over the Northern Rockies.

Precipitation arrives Sunday afternoon in northwest Montana and
increases eastward through Monday morning. A strong cold front
will accompany this system, bringing temperatures down to
seasonable daytime highs for Monday through the rest of the week.
The pressure gradient aligns for strong westerly winds with the
frontal passage. Gusts of 30-40 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.

As the Monday/Tuesday system departs, the upper level jet stays in
a favorable position to transport moisture into the Northern
Rockies. This moisture feed, along with good jet dynamics, will
bring another round of precipitation on Wednesday into
Thanksgiving Day. Cold air remains in place, so snow is the more
likely precipitation type. The pattern stays active through the
week, so holiday travelers should continue to check in on forecast
updates as the week evolves.

&&

.AVIATION...Aviators should be prepared for valley fog and low
stratus cloud decks across the Northern Rockies airspace this
morning. Dry air descending from the north is clearing midlevel
stratus early this morning, replacing those higher clouds with
shallow valley cloud decks and decreased visibility due to fog.
Expect clearing by late morning as inversions break.

&&

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

$$