647
FXUS65 KMSO 241915
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
115 PM MDT Sun Aug 24 2025

.DISCUSSION...

- Degraded air quality due to wildfire smoke continues, mainly
  across central Idaho.

- Thunderstorm chances increase from south to north Tuesday
  through Friday.

- Potential for flash flooding due to heavy rainfall from slow-
  moving storms and high atmospheric moisture Tues, Weds, and
  Thurs.

Not much has changed in the forecast with regards to wildfire
smoke, dry conditions, and the persistent nighttime/daytime heat
in central Idaho. Smoke continues to degrade air quality from
large wildfires in the Clearwater Mountains and maintains a
presence in valleys where it remains stagnant. Heat advisories
also remain in effect for low valleys from roughly Orofino south
through Riggins to account for hot days followed by warm nights
possibly affecting those with heat sensitivities.

Confidence in the forecast period covering Tuesday through Friday
is increasing due to consistent model agreement in anomalously
high atmospheric moisture present during this timeframe. Monsoon
moisture meanders further northward with each passing day,
beginning Monday and really ramping up Wednesday and Thursday. By
Wednesday, available atmospheric moisture will be around 200% of
normal. As such, thunderstorms will pose a high threat for
extremely heavy downpours. There is no cold front to drive these
storms or kick them out of the area, so while that limits the
supercell potential for developing storms, it also means any
storms that do form will traverse very slowly. Thus, the potential
for flash flooding remains high. Take heed of the forecast if you
live near a wildfire burn scar, or in/near an area with a history
of flash flooding, or have plans to be anywhere near either of
these two locations during the Tuesday through Friday timeframe.

Confidence also remains high that northwest Montana, namely areas
along and north of Highway 200, will see the least amount of
rainfall and storm development this week.

&&

.AVIATION...Light east-northeast winds will continue through
Monday. As with yesterday, periodic gusts of 15-20kts will impact
KMSO after 24/2200Z. Reductions in visibility will continue to be
prominent across north-central Idaho, including KGIC due to
wildfire smoke.

&&

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

&&

$$