805
FXUS65 KMSO 120817
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
217 AM MDT Thu Jun 12 2025

.DISCUSSION...

KEY MESSAGES:

- Showers will continue in northwest Montana this morning.

- Thunderstorms will be a near daily occurrence across the region
  with above average temperatures and humid conditions.

- Chance for strong thunderstorms again Friday.

Small shortwaves embedded in the moist, southwest flow over the
region combined with orographic lift (up-slope flow forced by the
terrain), will cause another round of showers and possibly
isolated thunderstorms in northwest Montana this morning. Then
with the warming of the day, the region will become unstable once
again this afternoon. Showers and thunderstorms will be
concentrated over the terrain where orographic lift and the daily
mountain-valley breeze circulation will conspire to cause them to
initiate.

The southwest flow remains over the region for at least another
week. This means the potential for afternoon thunderstorms will be
a daily occurrence, and the locations of storms will be dependent
on where shortwaves happen to be moving through the flow. These
shortwaves are a very subtle feature of the flow, so we do not
have good predictability with them more than about 24 hours out
most of the time.

A larger trough embedded in the southwest flow moves through
Friday and supports some stronger thunderstorms. These storms will
initiate over central Idaho and western Montana and move to the
northeast. Most models, including machine learning models, are
putting the strongest storms east of the Continental Divide. If
any severe storms do form west of the Continental Divide, they`ll
most likely be east of Highway 93. In any case, the probability of
severe thunderstorms on Friday west of the Continental Divide sits
at around 5%.

&&

.AVIATION...Southwest flow and a moist air mass mean that
convection will continue again today. Some showers will be in the
vicinity of terminal KGPI this morning, with convection becoming
more widespread across the region around 12/20Z. Terminal KBTM
will have the best chance for a significant thunderstorm, while
terminals west of there will likely only see thunderstorms in
their early, developing stages.


&&

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

$$