553
FXUS65 KMSO 012102
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
202 PM MST Mon Dec 1 2025

.DISCUSSION...

KEY MESSAGES:

-  Widespread Winter Travel Impacts (TonightTue): Snow is
   expected to cover roads, creating slick conditions for
   virtually all elevations.

-  Active Pattern Continues (Late Week): A mix of moisture and
   cold ground temperatures could bring additional rounds of slick
   travel.


Confidence remains high in a widespread snow event evolving across
western Montana and north central Idaho tonight through Tuesday.
Modified arctic air remains in place across western Montana,
allowing for snow to fall at all elevations. As incoming moisture
interacts with the cold dome of air in place, snow will develop,
becoming moderate at times overnight into Tuesday. For the most
part, valley snowfall of 1 to 3 inches will be widespread in
western Montana. Locally favored areas such as the Swan/Mission
valleys northwards into Big Fork and the eastern half of the
Flathead Valley could see upwards of 4 to 8 inches due to upslope
flow and lake enhancement.

The forecast for Idaho is a bit more tricky, but winter weather
advisories have been expanded to include lower elevations such as
Grangeville and Orofino. Temperatures will likely hover right
around freezing in these areas, but a burst of higher intensity
precipitation overnight tonight is expected to bring a period of
accumulating snow as low as 1000 ft in elevation. Snow may linger
into Tuesday evening on the Camas Prairie in particular as the
upper level flow turns more northerly (upslope). We will keep an
eye on the scenario and the potential for additional winter
products continuing into Tuesday evening.

Bottom line: Widespread winter driving conditions are anticipated
tonight into Tuesday. Winter weather advisories are in place and
those who plan to travel should anticipated slick, snowcovered
roads, especially late tonight into Tuesday morning.

Following a brief lull Wednesday, active weather returns late
Thursday. A deep trough over the central Pacific will direct a
long fetch of subtropical moisture toward the Northern Rockies by
Friday and Saturday. Forecast details regarding precipitation type
remain complex. Mild air aloft will likely erode any cold air
left over the region raising snow levels as high as 5000 feet by
Friday afternoon, but the timing of this occurring is still
somewhat questionable. Friday morning in particular could be a
sloppy mess for valley locations with some areas switching to rain
while others may continue to see snowfall. Valleys that do switch
to rain may see ice on roadways due to cold ground temperatures.
For those who enjoy backcountry recreation, this weekend into next
week could see a marked increase in snowpack above 5000 feet!

&&

.AVIATION...Snow will arrive this afternoon at KGPI ,KMSO, and
KHRF. Low stratus decks and lowered visibility associated with
snowfall will persist tonight and into Tuesday through about
midday. Snow will reach KBTM and KSMN this evening. Ceilings down
to about 1000 ft and 2 SM visibility will accompany precipitation.
Expect obscured terrain across all mountain ranges in the Northern
Rockies through Tuesday afternoon.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 8 PM this evening to 5 PM MST
     Tuesday for Bitterroot/Sapphire Mountains...Butte/Blackfoot
     Region.

     Winter Weather Advisory until noon MST Tuesday for
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 5 PM MST Tuesday for
     Potomac/Seeley Lake Region...West Glacier Region.

     Winter Weather Advisory until noon MST Tuesday for
     Flathead/Mission Valleys...Lower Clark Fork Region.

     Winter Weather Advisory from 8 PM this evening to 2 PM MST
     Tuesday for Missoula/Bitterroot Valleys.

ID...Winter Weather Advisory from 7 PM this evening to 4 PM PST
     Tuesday for Northern Clearwater Mountains...Southern
     Clearwater Mountains.

     Winter Weather Advisory from 10 PM this evening to 9 AM PST
     Tuesday for Orofino/Grangeville Region.

     Winter Weather Advisory from 7 PM this evening to 11 AM PST
     Tuesday for Lower Hells Canyon/Salmon River Region.

&&

$$