856
FXUS65 KMSO 101855
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1155 AM MST Mon Nov 10 2025

.DISCUSSION...

KEY MESSAGES:

- Stable, stagnant conditions continue through Wednesday with fog
  potential.

- A mild atmospheric river on Thursday brings rain to the region.

- A pattern change starts Friday with falling snow levels with
  continued active weather into next week.

A broad, potent ridge over the region today is weakening as a
shortwave moves through it. It will cause some showers in
northwest Montana this afternoon and evening and down into
portions of west central Montana. Snow levels will remain high
enough and precipitation amounts low enough that little to no
impact is expected.

The now weakened ridge will remain in place helping to keep valley
cold pools in place through Wednesday. Tuesday and Wednesday
mornings will see patches of valley fog in the mornings. Fog will
be denser around rivers.

The pattern change begins with a mild atmospheric river which is
in place by Thursday. Model timing has trended sooner recently
with the potential for some light rain starting by Wednesday in
Northwest Montana. Recent forecasts have trended down with the
rain amounts as a result of models trending towards a deeper
trough with more southerly flow. That will keep most of the
moisture west of our area with only the western portions of
central Idaho and northwest Montana picking up more than a tenth
of an inch of moisture.

Then snow levels fall Thursday night. Friday onward will see much
more of the region getting snow. This is a very dynamic pattern
with sharp troughs and ridges, so there is considerable
variability on the timing and snow amounts through the weekend.
Models have recently trended slightly lower, bringing the 90th
percentile 3-day snow total at Lookout Pass down from over 24
inches to closer to 16 inches. Again, that is the 90th percentile
forecast that is coming down, so the models are starting to
discount the more extreme solutions. It`s also interesting to see
that the snow and rain forecasts through the weekend barely show
up on the European EFI tool which highlights climatologically
uncommon events.

That said, the Fall season is progressing and snow levels are
coming down, and much of the back country remains open through
November. So while we`re not looking at a big weather event this
weekend, we are expecting a few inches to a foot of snow in the
mountains from Friday through Sunday. Mountain passes will be
impacted with some snow and if you`re in the back country, it will
be critical to be prepared for moderate to heavy snow.

The active weather pattern continues through next week with
frequent troughs and cold fronts, along with frequently rising and
falling snow levels.

&&

.AVIATION...A potent high over the region is causing stable
conditions allowing for valley fog to develop in the mornings.
Terminal KGPI is the most likely to be impacted by this again
tomorrow morning due to models showing increasing dew points with
height. Elsewhere, terminal KMSO will likely see river fog in the
vicinity of the airport, but drier conditions aloft (in model
soundings) make it less likely than KGPI to develop fog. By late
Wednesday a weak atmospheric river moves into the region causing
thicker cloud cover and increasing chances of precipitation to end
out the week.

&&

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

$$