970
FXUS65 KMSO 180943
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
Issued by National Weather Service Spokane WA
243 AM MST Tue Nov 18 2025

.DISCUSSION...

KEY MESSAGES:

-Showery weather through Wednesday

-Fog chances increase towards Thursday through Saturday

-Increasing chances for rain across northwest Montana Saturday,
 then remainder of region by Sunday.

-Snow above 5000 feet by Sunday, 4500 feet by Monday.

-Thanksgiving Week still looks active with colder, wintry weather
 including pass-level snow and possible valley snow, but
 uncertainty is great.


Radar and satellite imagery shows a similar scenario to 24 hours
ago, with rain showers across north central Idaho, moving slowly
to the north-northeast, towards Northwest Montana. A weak front
will move across the region this afternoon, but still expect a
fair amount of clouds, just with an added light westerly breeze.
There may be enough breaks tonight to allow fog formation.

On Wednesday, a weak trough passage is on tap. There may be a few
spotty showers around. Again possible fog formation by Wednesday
night into Thursday.

By Friday, high-level moisture begins to stream in from the west
as mostly high clouds. There may be low clouds or fog in the
morning. The chance for showers in the mountains increases by late
day into Saturday. There is considerably lower chance for showers
on Saturday south of Missoula towards Salmon and Butte, and also
across southern Idaho County. Highs still running 10 to 15 degrees
above average. Snow levels on Saturday and Sunday will be near
5000 feet across northwest Montana and 6500 feet to the south.
Total precipitation over the weekend will be higher in the
mountains to the north where there is a 75% chance for at least
0.25, and on the higher end, a 25% chance for 0.60 to 1.00 in
the mountains along the Idaho/Montana border. For the cold front
pattern Monday/Tuesday to start the Thanksgiving week, the models
have shown a lot of variability over the past several days. We
have high confidence that there will be a cold front passage
(90%), some valleys may receive wind gusts over 25 mph (30-60%),
and temperatures will likely fall to colder readings than we have
seen so far this November, 75% chance for highs less than 40
degrees on Tuesday in western Montana, and 35% chance in the lower
Idaho valleys. The amount of precipitation varies greatly for
this front: only a skiff of snow in mountain passes on one end of
the spectrum, and in the high end, 4 to 6 inches in the mountains
through Tuesday morning.

By Wednesday, there is still a 60 to 80 percent chance that highs could
be around freezing or colder across western Montana, but milder
in the lower elevations of Idaho (30s to 40). Those probs decrease
by Thanksgiving into Friday which suggests moderation. Snow
showers could persist in the mountains Tuesday into Wednesday.
This post-frontal, unstable northwest flow is a common setup that
could also bring periodic snow showers down to some valley floors.

The ensembles appear to be latching onto a push of Pacific
moisture by the day after Thanksgiving (Friday) and/or into
Saturday. This could bring the chance for snow to the regionsnow
levels are to be determined (NBMs middle of the road forecast
range of 1000 feet to 2500 feet on Friday).

&&

.AVIATION...An unsettled pattern will persist through Tuesday, resulting in
frequent mountain obscurations and periodic low ceilings. Overnight and
morning fog remains a concern in areas where partial clearing occurs,
particularly at KGPI and KMSO.

Shower activity will gradually diminish this afternoon, primarily impacting
northwest Montana. By Tuesday morning, a sharper shortwave will drive a
weak cold front toward the Idaho/Montana border, accompanied by a distinct
band of rain and snow (snow levels near 6500 feet). Precipitation coverage
is expected to decrease as the front tracks eastward later in the
day.

&&

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

$$