786
FXUS65 KMSO 301937
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
137 PM MDT Mon Jun 30 2025

.DISCUSSION...

KEY MESSAGES:

-  Hot temperatures through Wednesday

-  Gusty storms in Lemhi County & SW Montana Tuesday afternoon

-  Thunderstorms across the region each day Wednesday onward

Hot daytime temperatures will persist through Wednesday as high
pressure remains over the Northern Rockies. Warm overnight lows
are also expected in the lower valleys of north-central Idaho,
where a heat advisory is in effect.

Moisture will begin increasing across Lemhi County and southwest
Montana on Tuesday, with high-resolution models now indicating
potential thunderstorm development. Any storms that form are
expected to be high-based and will likely produce gusty outflow
winds.

The ridge shifts eastward Wednesday, setting up southwest flow- a
classic thunderstorm pattern for central Idaho and western
Montana. With the recent heat and dry conditions, strong winds
will be the main threat at first. Machine learning and AI models
continue to indicate some risk of severe storms Wednesday.

Model guidance agrees that southwesterly flow will persist through
the week and into the weekend, but differs on the exact timing and
strength of thunderstorm-producing shortwaves. This pattern favors
daily thunderstorms, some potentially strong with gusty winds,
heavy rain, and hail. If you have outdoor plans, stay weather-
aware and have a plan in case a storm approaches.

&&

.AVIATION...Hot daytime temperatures will continue under strong
high pressure, which may contribute to density altitude concerns.
High-resolution models now indicating potential thunderstorm
development across Lemhi County and southwest Montana Tuesday
afternoon, which may impact KSMN and KBTM. Any storms that form
are expected to be high-based and will likely produce gusty
outflow winds.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Heat Advisory until 9 PM PDT Tuesday for Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

&&

$$