170
FXUS65 KMSO 171909
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
109 PM MDT Fri Oct 17 2025

.DISCUSSION...

KEY MESSAGES:

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

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

Satellite imagery this afternoon indicates a fast-moving
disturbance moving north to south near the Canadian border, as
well as a well-formed low pressure circulation off the coast of
Alaska. In the near term, the Canadian disturbance will bring
gusty winds and chances for precipitation this afternoon.
Precipitation will move from north to south with the shortwave.
Expect winds of about 30 mph across the higher terrain and some
valleys of western Montana. Gusts to 40 mph will grace the
Continental Divide. Boaters on Flathead Lake should be prepared
for strong winds and choppy seas. 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 short-lived ridge of high pressure will build on Saturday as the
Alaskan circulation moves south and east towards the Pacific
Northwest. After a day of mostly fair weather on Saturday, that
circulation will arrive in Washington state on Sunday. The
pattern turns active as a cold front associated with this system
enters the Northern Rockies. Expect widespread showers and gusty
winds on 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 mixed with snow by Monday morning, snow
accumulation will be minimal at best.

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...A cold front will move through the region today,
bringing widespread west winds. Gusts up to about 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 through about 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 until 7 PM MDT this evening for
     Flathead/Mission Valleys.

ID...None.
&&

$$