640
FXUS65 KMSO 231324 CCA
AFDMSO

Area Forecast Discussion...CORRECTED
National Weather Service Missoula MT
724 AM MDT Sat Aug 23 2025

.DISCUSSION...

KEY MESSAGES:

- Locally degraded air quality through the weekend due to
  increased wildfire smoke and stable conditions, especially in
  north central Idaho

- Heat intensifies this weekend, with heat advisories in place for
  lower valleys of north central Idaho.

- Increased chances for thunderstorms early next week as monsoon
  moisture moves northwards from the Desert Southwest.

Satellite imagery early this morning reveals a strong ridge of
high pressure across the Northern Rockies, with abnormally dry
air in the low levels of the atmosphere. Area wildfires have
continued to burn actively overnight given dry and warm air across
midslope and high elevation areas. An easterly gradient remains
in place this morning, with surface observations highlighting a
surface high east of the divide, with a thermal low across the
Inland Northwest.

A warming trend remains on track this weekend, with temperatures
reaching the low to mid 90s for western Montana valleys to low
100s for the lower valleys of north central Idaho. Heat advisories
continue across the lower valleys of Idaho where hot daytime
temperatures coupled with warm overnight temperatures will cause
heat stress, especially to those who are sensitive to the heat.
This heat will be compounded by wildfire smoke impacts as fires
remain active in the Clearwater Mountains and easterly winds
funnel smoke into the lower elevations during the overnight and
morning hours through Sunday.

The warm weather pattern will continue into mid next week.
Forecast models continue to indicate monsoon moisture will slowly
drift northwards, reaching Lemhi County as early as Monday and
into southwest Montana and north-central Idaho by Tuesday.
Thunderstorm activity will likely ramp up, possibly impacting much
of the area by Wednesday/Thursday time frame.

&&

.AVIATION...Light east-northeast winds will continue across the
Northern Rockies airspace through Saturday morning. Easterly winds
will continue along the divide through this afternoon, with a
northerly wind shift expected across west-central Montana and
north-central Idaho, with gusts of 10-15kts. Otherwise, local and
regional wildfire smoke will continue to cause areas of lowered
ceiling and visibility in smoke, obscuring the terrain at times.
The lowest visibilities will focus across north central Idaho, in
the vicinity of KGIC.

&&

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

&&

$$