827
FXUS65 KMSO 171853
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1253 PM MDT Sun Aug 17 2025

.DISCUSSION...

KEY MESSAGES:

-  Thunderstorms capable of gusty outflow winds and brief heavy
   rain through this evening.

-  Above-normal temperatures through mid week.

Numerous showers and scattered thunderstorms have developed
across central Idaho into southwest Montana early this afternoon.
This will remain the theme through this evening, as above normal
moisture from the Pacific and modest instability fuels additional
rounds of showers and thunderstorms across these areas. Stronger
storms will be capable of producing brief heavy rain, with the
risk for outflow winds of 30-50 mph being focused near and along
the Divide. Flood prone areas, including recent burn scars, will
be monitored closely through this evening. Theres a 10% of
excessive rainfall leading to flash flooding across southwest
Montana in recent burn areas, including the Daly burn scar over
Skalkaho Pass. Storm motions of 20-25kts will limit the overall
risk for flash flooding and therefore, no watches have been
issued.

A ridge of high pressure will strengthen and amplify across the
Four Corners region Monday into Wednesday this week. This will
place the Northern Rockies under southwesterly flow, with enough
moisture and instability for additional rounds of showers and
thunderstorms each afternoon and evening.

Model ensemble guidance continues to highlight a disturbance
moving through the Northern Rockies during the Wednesday to
Thursday time frame, which will cause the upper level flow to
become westerly. This disturbance will allow temperatures to cool
down to seasonal readings.


&&

.AVIATION...Thunderstorms will continue to impact portions of
southwest Montana and south central Idaho through this evening.
Aviation impacts from thunderstorms and rain will be most likely
at terminals KBTM, KSMN, KHRF, and KMSO through 18/0300Z.
Lightning, heavy rain, small hail, and gusty outflow winds are all
possible with storms that move over terminals. Conditions further
north will remain benign and free from thunderstorm impacts.
Continued unsettled southwesterly flow will persist into Monday.


&&

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

$$