053
FXUS65 KMSO 231853
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1253 PM 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 advisories remain in place for lower valleys of north
  central Idaho through mid-week.

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

Wildfire smoke continues to degrade air quality across the region,
with the worst being felt across central Idaho as stable
conditions and a light easterly gradient keep the thickest smoke
trapped across Idaho and Clearwater counties. Elsewhere,
vertically integrated smoke has been present, but with less
effects to air quality degradation. With high pressure expected to
persist through roughly mid-week, more widespread air quality
issues may occur. So far, northwest Montana has seen the least in
the way of wildfire smoke.

Typical summertime temperatures will continue across the Northern
Rockies, with the exception of central Idaho valleys where
temperatures will range between 100 to 110 degrees with little
relief in the way of overnight cooling. As such, heat advisories
remain in place through Wednesday for locations such as Orofino,
Grangeville, Riggins, etc. due to the lack of cooling at night to
provide at least some relief to folks with heat sensitivities.

A change in the pattern comes early to mid-week when monsoonal
moisture meanders northward from the Four Corners region, bringing
with it very high precipitable water values (about 150% to 200%
of normal). This means the amount of available moisture in the
atmosphere by Wednesday and Thursday could cause very heavy
downpours from thunderstorms that initiate during this period. At
this time, available instability seems quite limited, so the
threat for potent thunderstorms remains low as well. That being
said: this could turn into a flash flood concern very quickly if
conditions shift even a little. Those with plans near known flood
prone areas or wildfire burn scars should remain vigilant to the
forecast by mid to late next week.


&&

.AVIATION...Light east-northeast winds will continue across the
Northern Rockies airspace through Sunday. Reductions in visibility
will be prominent at KGIC due to wildfire smoke, however smoke
elsewhere will be more vertically integrated and thus, limit any
impacts to visibility. Easterly winds will diminish shortly after
24/0400Z.

&&

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

&&

$$