150
FXUS65 KMSO 151843
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1243 PM MDT Sun Jun 15 2025

.DISCUSSION...

KEY MESSAGES:

-  Scattered showers/few thunderstorms, mainly southwest Montana,
   this afternoon/evening

-  Thunderstorm coverage expands northward on Monday afternoon

-  Trending toward much cooler/increased precipitation chances
   next weekend

Overall, southwest flow continues the next few days with daytime
temperatures running about 10 degrees above normal. There will be
occasional showers/thunderstorms, mainly I-90 southward, focused
in the afternoon/evening.

Speaking of this afternoon: Mid-level moisture and weak lift
embedded in southwesterly flow will lead to a few sprinkles and
light showers across the Northern Rockies through early evening.
Cloud cover in general is limiting convective potential but
clearing behind the cloud shield is allowing for isolated
convection over the ID Panhandle and may continue into northwest
Montana. Another exception is southwest Montana/Lemhi County,
where sunshine has allowed for modest instability with scattered
showers and thunderstorms anticipated for the afternoon. There is
a slight potential (10% or less) around Butte for a strong
thunderstorm with gusty outflow winds over 40 mph and small hail.

Showers diminish this evening but the moisture axis remains
across southwest Montana with a few remnant showers/rumbles of
thunder overnight. The moisture axis lifts slightly northward on
Monday into west- central Montana with another round of scattered
afternoon showers and thunderstorms, mainly from I-90 southward.
Once again, a storm or two may strengthen enough for gusty outflow
winds and small hail.

Given an approaching weak trough and left-over moisture, nocturnal
showers and a few rumbles of thunder may continue from I-90
southward Monday night into Tuesday morning. Weak ridging builds
in Tuesday afternoon helping to dry things out and diminish
precipitation chances.

Ridging bumps up over the Northern Rockies Wednesday into Thursday
for a slight uptick (3-6 degrees) in daytime temperatures.
Afternoon winds will also be breezier (gusts 25-35 mph),
especially Wednesday as the westerly pressure gradient tightens.
There are hints that mid- level moisture will increase on Thursday
afternoon, thus precipitation chances may need to be adjusted
upward in the coming days. Friday appears to be a transition day
with breezy winds, slightly cooler temperatures, and rain chances
but much will depend on the timing of an approaching trough.

Little has changed with the trough potential for next weekend
(June 21-23). Ensemble clusters remain in very good agreement with
a decent upper level trough pressing into the Northern Rockies
leading to much cooler temperatures and an increase in
precipitation chances. Much will depend on how the trough
evolves either as a closed low or an open wave, as the closed low
would allow for widespread precipitation and lower snow levels compared
to an open wave. Considering it will be late June, it`s noteworthy
that middle of the road snow levels are forecast at 6500-7000
feet but would be another 1000 to 1500 feet lower if a strong
closed low develops. This would open up a potential for impacts
to back country users including in Glacier National Park.
Gardeners may need to be aware of frost by Monday morning as well,
mainly along the Divide.




&&

.AVIATION...Mid-level moisture and weak lift embedded in
southwesterly flow will lead to a few sprinkles and light showers
across the Northern Rockies through early evening. Cloud cover in
general is limiting convective potential this afternoon but
clearing behind the cloud shield is allowing for isolated
convection over the ID Panhandle and may continue into northwest
Montana. Another exception is southwest Montana/Lemhi County,
where modest instability will lead to scattered showers and
thunderstorms, including at KBTM and KSMN. There is a slight
potential (10% or less) around Butte for a strong thunderstorm
with gusty outflow winds over 40 mph and small hail.

Shower activity diminishes early this evening but the moisture
axis will remain across southwest Montana for a slight chance of
showers/rumble of thunder overnight. The moisture axis lifts
slightly northward on Monday into west- central Montana with
another round of scattered afternoon showers and thunderstorms,
mainly from I-90 southward.


&&

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

$$