052
FXUS65 KMSO 170659
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1259 AM MDT Fri Oct 17 2025

.DISCUSSION...

KEY MESSAGES:


-  Scattered showers and gusty winds (choppy lake conditions)
   this afternoon/evening

-  Minor travel impacts are possible over mountain passes Sunday
   night/Monday due to snowfall


A fast-moving disturbance will move through the region today,
bringing gusty winds during the afternoon and early evening.
Probabilities for gusts reaching 30 mph remain around 40-60%
across the higher terrain and valleys of western Montana. A lower
chance (20-30%) exists for gusts exceeding 40 mph, mainly along
the Continental Divide and into southwest Montana, particularly in
association with showers.

Model guidance has increased confidence in strong winds over Flathead
Lake, prompting the issuance of a Lake Wind Advisory. Expect choppy
lake conditions this afternoon and evening. Showers will be most
frequent over the higher terrain but may occasionally move across
valleys, locally enhancing wind gusts. Snow levels will stay above
5000 feet, with only minor accumulations expected in the high
backcountry.

A shortwave ridge builds in Saturday, offering a brief period of dry,
pleasant fall weather. The pattern turns active again on Sunday as a
cold front linked to the remnants of an atmospheric river
approaches the region. Widespread showers and gusty winds are
expected Sunday morning through the afternoon, once again
producing choppy lake conditions.

Snow levels will begin near 7000 feet on Sunday but will drop sharply
to 4500 feet by Sunday night. The main concern will be
accumulating snow over mountain passes late Sunday into Monday
morning, enhanced by lingering showery, upslope flow. Current
ensemble means suggest 2-4 inches of snow for Lolo, Lookout, Lost
Trail, and Marias Passes, with 4-8 inches in the higher terrain.
These conditions will create cold, snowy, and potentially
hazardous travel for backcountry users. While some valley
locations may see rain mix with snow by Monday morning, no
accumulation is anticipated.

Looking ahead, much of next week appears mild, with seasonable to above-
normal temperatures and occasional light showers. However,
ensemble trends hint at the potential for a more significant
atmospheric river event around October 25-27 with a moderate risk
of heavy mountain snow. Stay tuned for updates as details become
clearer.

&&

.AVIATION...Changes are underway today as a cold front moves through the
region. Widespread west winds, gusting up to 25 knots, will
develop across most terminals by 17/1900Z. There remains a low
(~20%) probability for gusts reaching or exceeding 35 knots,
particularly in association with stronger showers or storm
outflows.

Scattered showers and an isolated thunderstorm are possible between
17/1900Z and 18/0600Z under west-northwesterly flow. These could
briefly reduce visibility and lower ceilings, leading to a
temporary deterioration in flight conditions.

Clearing and drying are expected tonight into Saturday, with the
potential for patchy morning valley fog or low stratus to
redevelop.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Lake Wind Advisory from 11 AM this morning to 7 PM MDT this
     evening for Flathead/Mission Valleys.

ID...None.
&&

$$