492
FXUS65 KMSO 110847
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
247 AM MDT Sat Oct 11 2025

.DISCUSSION...

KEY MESSAGES:

- A noticeable change has arrived. Expect chilly, showery, and
  breezy conditions today.

- A colder push of air arrives Sunday, bringing a transition to
  valley snow and gusty northerly winds, especially in northwest
  Montana.

- Monday will be cold and blustery across the region, with morning
  wind chills dipping into the teens and 20s, and a transition to
  valley snow across western Montana and the higher valleys of
  central Idaho.

The trough of low pressure has already entered the region,
bringing an abrupt end to our mild autumn weather. High
temperatures today will be around 15-20 degrees cooler than
yesterday, struggling to get out of the 50s. Scattered showers
will continue through the day, accompanied by breezy west winds
that will make it feel even colder. Those with outdoor plans today
should plan accordingly for these chilly and damp conditions.

A secondary push of even colder air is slated to move in on
Sunday. This will cause snow levels to begin to fall to valley
floors. As the colder air funnels in, expect gusty north and
easterly winds to develop Sunday morning, primarily impacting
northwest Montana. This will mark the beginning of the coldest
period of this event, with temperatures continuing to fall through
the day. Accumulating snow will create winter-like travel
conditions over the mountain passes.


Snowfall Timing and Impacts

Mountains: Snow will begin to accumulate in the mountains by this
evening. The most significant period of winter weather will be
from Sunday through Monday morning, with major accumulations
expected in the high terrain, especially within Glacier National
Park.

Mountain Passes: For travelers, the most impactful period is
expected from Sunday night through Monday morning. Accumulating
snow during this time will create slick, winter-like driving
conditions over all area passes.

Northwest Montana Valleys: These areas will see two distinct
periods of potentially hazardous weather.

 -  Sunday Morning: The initial change from rain to snow could be
    rapid. This quick transition as temperatures fall may cause a
    freeze on sidewalks and roadways, leading to brief but
    potentially very icy conditions.

 -  Sunday Night through Monday Morning: This will be the second,
    more prolonged impact period. Snow accumulations will be more
    likely on all surfaces, including roads, and another round of
    icy conditions is possible. Residents should be prepared for
    winter driving conditions for the Monday morning commute.

Dropping snow levels by Monday morning is expected across western
Montana and the higher valleys of north-central Idaho and Lemhi
County with more widespread impacts from rain changing to snow.
This is when the Butte/Blackfoot region is most likely to have
accumulations on all surfaces along with icy conditions.

Monday will remain the coldest and windiest day of the event.
Widespread gusty winds will combine with the cold temperatures to
produce morning wind chills in the teens and 20s. Blowing and
drifting snow will also be possible, particularly near the
mountain passes and the Continental Divide.

Temperatures will slowly begin to moderate on Tuesday as the
winds subside, but conditions will remain below average for mid-
October. The unsettled pattern looks to continue, with chances for
more showers later in the week.


&&

.AVIATION...Showery conditions with increasing westerly winds are
expected today with mountain obscurations expanding and becoming
widespread by this evening. Ceilings and visibility will lower
further tonight and on Sunday as colder air moves in, changing
all precipitation to snow in northwest Montana. Gusty
north/northeast winds will create LLWS potential at KGPI Sunday.
Snow levels will continue to lower Sunday night with most of the
valleys of western Montana and the higher valleys of central Idaho
transitioning to snow by Monday morning.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 6 PM this evening to noon MDT
     Monday for Bitterroot/Sapphire Mountains...Butte/Blackfoot
     Region...Lower Clark Fork Region...Potomac/Seeley Lake
     Region.

     Winter Storm Watch from this evening through Monday morning for
     Kootenai/Cabinet Region.

     Winter Storm Warning from 6 PM this evening to noon MDT Monday
     for West Glacier Region.

ID...Winter Weather Advisory from 5 PM this afternoon to 11 AM PDT
     Monday for Northern Clearwater Mountains...Southern
     Clearwater Mountains.

     Winter Weather Advisory from 6 PM this evening to 6 AM MDT
     Monday for Eastern Lemhi County...Western Lemhi County.

&&

$$