122
FXUS65 KMSO 162008
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
208 PM MDT Wed Jul 16 2025

.DISCUSSION...

KEY MESSAGES:

- Breezy, warm and dry days are expected through the weekend.

- There`s a 65 percent chance that a cooler, wetter and breezy
  weather system could impact northwest Montana on Monday.

The unusual weather system from yesterday left residual cloud
cover across portions of the Divide this morning into the
afternoon. Fair-weather cumulus clouds have developed over the
mountains in northwest Montana, likely a result of the copious
amounts of rainfall that occurred there. Multiple locations
received well over 0.50 of rainfall, and a few mountain locations
recorded over an inch, and over 2 inches across far northwest
Lincoln County! Low temperatures got real close to the freezing
mark in Polebridge, Olney and in a few locations west of Marion
this morning. Also, wildfire smoke could be smelled in the air
across western Montana as this system had drawn in smoke from
Canada.

The upper level flow supports breezy westerly winds for both
Thursday and Friday, especially from Lemhi County into southwest
Montana. On Thursday evening, a weak cool front will push
westwards across the Glacier NP Region towards Flathead Lake.
Right now, the northeasterly winds may generally be 10 to 15 mph,
with a few higher speeds through channeled terrain. A few
thunderstorms may develop in Glacier National Park Thursday
afternoon and evening.

The heat builds on Friday as highs will reach the 90s across
western Montana, and lower 100s in the lower valleys of north-
central Idaho. A wave may initiate a few thunderstorms across
southwest Montana in the afternoon. Strong wind gusts, heavy
rainfall, small hail and lightning would be the main threats,
generally affecting Silver Bow County southwards.

A weak cool and dry front will move through Friday night across
the region. Highs Saturday will be 5 to 8 degrees cooler than
Friday. But it will kick up the westerlies by the
afternoon...generally up to 25 mph in the western Montana valleys,
but closer to 30 mph from Lemhi County to Butte. This could make
lakes in those regions, like Georgetown Lake, kind of choppy and
hazardous for small craft.

By Sunday, the upper atmosphere configuration will be such that an
anomalously deep trough will be over the Pacific Northwest. This
will cause temperatures to be a few degrees cooler, but keep it
breezy.

On Monday, ensemble guidance depicts a cutoff low developing over
Washington and Oregon State. This setup is eerily similar to the
storm that we just encountered on Monday and Tuesday. There could
be a cold front passage from Canada, and it could bring wet
conditions across northwest Montana. The latest NBM depicts 50 to
65 percent chance for total rainfall amounts to exceed 0.09" from
Monday and Tuesday. Stay Tuned.



&&

.AVIATION... Fair weather cumulus clouds have develop in the
higher terrain, especially over northwest Montana. These clouds
will diminish after sunset this evening. The residual ground
moisture from yesterday`s storm will allow for the development of
patchy fog and/or low stratus in the valleys of northwest Montana,
potentially impacting KGPI by 17/10z. The remainder of the
terminals are expected to have fair flying conditions for the next
24 hours.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$