633
FXUS65 KMSO 252029
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
129 PM MST Tue Nov 25 2025

.DISCUSSION...

KEY MESSAGES:

- Unsettled Holiday Travel (Wednesday & Thanksgiving): Expect
  widespread light snow along the ID/MT border and across western
  Montana tonight Wednesday morning. Risk for wintry mix/freezing
  rain along I-90, with snow in northwest Montana Thursday
  morning.

- Winter Weather Impacts Increase Thursday Night-Friday: Anyone
  with post-Thanksgiving travel plans should monitor the forecast
  closely.

Today through Thanksgiving:
Satellite imagery this afternoon shows Pacific moisture streaming
inland, while cloud cover keeps valley atmospheres stable.
Confidence is increasing for widespread, prolonged light snow
beginning this evening (6 PM to Midnight) along the Montana/Idaho
border. Snow will expand across valley areas above 2,000 feet,
including the US-93 corridor, through Wednesday morning. Given the
busy holiday travel window, Winter Weather Advisories, have been
issued for the MT/ID border and western Montana valleys, where 1-3
inches of accumulation will likely cause travel disruptions.

The air mass is forecast to gradually warm Wednesday afternoon
into Thursday morning, lifting snow levels near or above 4,000
feet south of the I-90 corridor. While precipitation will lull
Wednesday afternoon, the next wave of Pacific moisture arrives
early Thursday. This brings a concern for a wintry mix along the
I-90 corridor, with a 20-30% chance of freezing rain in the
Missoula and Bitterroot valleys, as well as I-90 west of Missoula.
Conversely, cold air may remain trapped in the valleys of
northwest Montana through Thursday morning, supporting another
round of light snow north of I-90.

Thursday Afternoon through Friday:
Recent model runs highlight a dynamic, impactful winter weather
scenario developing for western Montana. The synoptic setup
features a warm front lifting through the region Thursday morning,
pushing valley temperatures into the mid-30s. This will produce a
period of rain, rain/snow mix, or wet snow in the lower valleys
Thursday afternoon, leaving road surfaces wet and above freezing.

The critical period begins Thursday evening as a modified arctic
front pushes south over the Continental Divide. This frontal
passage will bring falling temperatures and a transition to all
snow. Model cross-sections indicate a favorable environment for
mesoscale snow banding along the boundary, driven by anomalous
moisture and strong frontogenesis. A winter storm watch has been
issued for the Glacier Park region, where our confidence is
currently the highest for impacts from prolonged snow along the
arctic front and falling temperatures to create a favorable freeze
up scenario.

Based on historical events, the hardest-hit areas will likely
include:
   -Glacier Park Region: US-2 from West Glacier to Marias Pass.
   -Flathead & Mission Valleys.
   -US-93, I-90, Highway 200 corridors from Missoula towards the
    divide.

Snow will persist across all mountain passes through Friday.
Precipitation is expected to taper off Friday evening, leading to
a mostly dry but colder Saturday.

Extended Outlook (Next Week): An active northwest flow pattern
continues into next week, bringing renewed snow chances and
potential episodes of Arctic air spilling over the Divide.

&&

.AVIATION...Outside of lingering lowered cloud cover in northwest
Montana, VFR conditions are expected to prevail across the
forecast area through this evening. Aviation conditions will
deteriorate after around 06/0600Z as the next weather disturbance
approaches from the northwest, bringing lowering ceilings and
widespread precipitation. Valley flight categories are most likely
to drop to MVFR or IFR thresholds between 08Z and 12Z Wednesday as
light snow develops. A transition to a rain/snow mix is possible
after around 17Z in the valleys of west-central Montana as
precipitation transitions to showers.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 11 PM this evening to 11 AM MST
     Wednesday for Bitterroot/Sapphire Mountains...
     Flathead/Mission Valleys...Kootenai/Cabinet Region...Lower
     Clark Fork Region...Missoula/Bitterroot Valleys...
     Potomac/Seeley Lake Region.

     Winter Storm Watch from Thursday afternoon through Friday
     afternoon for West Glacier Region.

ID...Winter Weather Advisory from 10 PM this evening to 10 AM PST
     Wednesday for Northern Clearwater Mountains...Southern
     Clearwater Mountains.

&&

$$