176
FXUS65 KMSO 171923
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1223 PM MST Mon Nov 17 2025

.DISCUSSION...

KEY MESSAGES:

 - Through Friday: Mild temperatures with light periodic showers.
   Patchy, locally dense fog likely during overnight and morning
   hours

 - This Weekend (Nov 22-23): Minor atmospheric river event. Snow
   levels of 4500-5500 feet, limiting winter impacts to pass
   levels

 - Thanksgiving Week: Pattern shift to colder, wintry weather.
   Increasing potential for valley snow and slick travel

Now through Friday: A split flow pattern will maintain mild
temperatures for mid-November. Periodic showers are expected to
persist through Wednesday morning. While snow accumulations on
mountain passes will generally be minor with limited travel
impacts, Wednesday morning bears watching. High-resolution models
suggest moderate shower activity around Marias and Lost Trail
passes, which could result in brief snow-covered roadways.

Locally dense valley fog will be a travel concern during the overnight
and morning hours throughout the week. By Thursday and Friday,
weak ridging builds in; this stable atmosphere will likely
facilitate more widespread valley fog.

This Weekend (Nov 22-23): Models continue to shift the upper-
level jet further north compared to earlier runs. If this
northward trend holds, precipitation amounts will further decrease,
and snow levels will rise. The latest NBM indicates 48-hour
precipitation totals of 0.40 to 0.70 inch across the ranges of
northwest Montana, with much lower amounts further south. With
snow levels forecast between 4500 and 5500 feet, road impacts
will likely be confined to minor travel difficulties on higher
passes with the latest snow forecast of 1 to 3 inches. Please stay
tuned as this forecast period evolves.

Thanksgiving Week: The pattern signals a transition to more
widespread, impactful wintry weather. High confidence remains that
a trough and cold front arriving later Monday into Tuesday will
deliver the coldest air so far this season. However, recent trends
suggest this trough may not be as deep as previously forecast,
which would initially limit valley snow accumulation.

Despite this, pass-level travel will likely become difficult due to a
combination of slick roads, reduced visibility, and gusty winds. The NBM
currently projects 3 to 7 inches of new snow on the passes, with an inch or
less for lower valleys Monday/Tuesday.

Looking further ahead, the NBM indicates a 60-70% probability of
high temperatures remaining at or below freezing for western
Montana valleys by the middle of next week. While there is still
model divergence regarding the depth of the arctic air, there is
growing support that the core of the coldest air will remain along
the Divide and points east through at least late next week. The
general pattern the second half of next week favors a showery
west to northwest flow, supporting additional snowfall
opportunities. In fact, this is a common setup for periodic
moderate snow showers to reach lower valley locations.

&&

.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.
&&

$$