907
FXUS65 KMSO 150739
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
139 AM MDT Sun Jun 15 2025

.DISCUSSION...

-  Few showers/thunderstorms, mainly southwest Montana, this
   afternoon/evening

-  Chance for thunderstorms will become more widespread on Monday

-  Trending toward much cooler/increased precipitation chances
   next weekend

Southwest flow continues into early next week as daytime temperatures
remain about 10 degrees above normal. Expect a few
afternoon/evening showers and thunderstorms today, mainly from
I-90 southward, particularly focused in southwest Montana.
Considerable mid-level moisture will stream into the Northern
Rockies today, bringing a few showers, but the cloud cover may act
to mute most convective potential. One exception is southwest
Montana, where models show modest instability by this afternoon
south of a line from Lost Trail Pass to MacDonald Pass. This
instability could allow for a thunderstorm to briefly become
strong enough for gusty winds over 40 mph and hail.

A more significant disturbance will drive an expansion in shower/thunderstorm
coverage Monday afternoon/evening, once again focused from I-90
southward. A similar theme remains with just enough
instability/shear for the potential of a strong thunderstorm or
two across southwest Montana. Overall, moisture and precipitation
chances decrease for Tuesday as the disturbance departs.

There will be a tighter westerly gradient Wednesday and Thursday
of next week, resulting in a slight uptick in winds. It also
looks mostly dry (aside from a few afternoon thunderstorms) with
daytime temperatures holding steady, near 10 degrees above normal.
Next Friday could be a transition day with winds, slightly cooler
temperatures, and rain chances by much will depend on the timing
of an approaching trough.

Speaking of a trough, ensemble clusters are in good agreement
with a fairly deep upper level trough pressing through the
Northern Rockies next weekend (June 21-23). Temperatures are
likely to drop to below normal levels along with an increased
probability for precipitation. 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 compared to an open wave.



&&

.AVIATION...Moisture embedded in southwesterly flow aloft will
result in cloud cover and about a 30% chance for afternoon
showers/thunderstorms over KBTM and KSMN today. The upper level
jet will be positioned over the Northern Rockies airspace. Winds
at KBTM have about a 50% chance of exceeding 20 kts by about
15/2100Z.


&&

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

$$