493
FXUS65 KMSO 221832
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1232 PM MDT Thu May 22 2025

.DISCUSSION...

KEY MESSAGES:

-  Cool and showery conditions through Friday morning

-  High pressure will build this weekend

-  Low pressure on Monday-Tuesday will bring chances for
   thunderstorms

A trough of low pressure is moving through the Northern Rockies
this afternoon, bringing widespread rain showers. The primary
circulation of the low will be over north-central Idaho. Idaho and
Lemhi counties, as well as southwest Montana, will see the most
rain as twenty-four hour precipitation totals will range from
about 0.20 to 0.70 inches by Friday morning. Snow levels stay
above about 7000 - 8000 feet. Showery conditions will persist on
Friday, with the focus of precipitation being in the higher
terrain, especially along the Continental Divide.

High pressure will build for the weekend. Daytime high
temperatures will climb into the 70s for the valleys of western
Montana and the 80s for the lower Salmon and Clearwater valleys in
Idaho. Sunday and Monday will be about 10 degrees warmer than
Saturday. While the ridge amplifies over the Northern Rockies, a
trough will dig along the West Coast. Low pressure and an
associated cold front will arrive by Monday evening. Southwesterly
flow aloft, along with daytime heating, Pacific moisture, and the
cold front, will be a good recipe for some afternoon/evening
thunderstorms on Monday. Precipitation will be favored south of
about I-90 and along the Divide on Monday. A shift to more
westerly flow aloft with some embedded moisture will keep showers
and thunderstorms in the forecast into midweek.

&&

.AVIATION...A shortwave trough is moving through the Northern
Rockies this afternoon. Expect brief reductions in ceiling and
visibility under intermittent rain showers into early Friday
morning. There will be chances for thunderstorms south of about
Interstate 90 (including KMSO) this afternoon after about
22/2000Z. Chances for thunder are about 20-30 percent for KSMN and
KBTM, and about 20 percent for KMSO.

&&

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

$$