586
FXUS65 KMSO 140825
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
225 AM MDT Fri Aug 14 2026

.DISCUSSION...


KEY MESSAGES:

-  Rounds of showers and thunderstorms with locally heavy rain,
   the potential for debris flows, and gusty winds (mainly western
   Montana) through today.

-  Temporary relief from smoke with easterly winds.

-  Gradual warming and drying trend this weekend, daily
   thunderstorm threat continues.

Scattered rain showers and isolated thunderstorms continued to
redevelop and move over western Montana and north-central Idaho
during the overnight hours into early this morning. Brief heavy
rainfall and occasional lightning occurred with these storms.
Lingering showers will continue to stream over western Montana
through mid-morning.

This afternoon, several rounds of showers and thunderstorms will
impact the Northern Rockies and will likely bring isolated
activity through the overnight once again. The main threat with
these thunderstorms will be brief heavy rainfall. Yesterday
afternoon, thunderstorms produced up to 0.40 inches per hour,
which can be expected with the thunderstorms today. The strongest
storms are expected between 3 PM and 9 PM, bringing a threat for
debris flows and excessive runoff to flood-prone areas of northern
Lemhi County and burn scars in the southern Bitterroot Valley. A
Flash Flood Watch may be needed to highlight areas at most risk
for impacts this afternoon and evening. Gusty and erratic winds
between 30-40 mph will also be a threat, that could blow around
unsecured objects and bring minor tree damage.

A ridge of high pressure will rebuild over the Northern Rockies
this weekend into early next week. Persistent southwest winds
aloft will continue to bring moisture into the region, keeping
atmospheric moisture high. This pattern will sustain daily chances
for afternoon showers and thunderstorms through next week,
preventing a full return to dry conditions. Wildfire smoke will
remain an ongoing challenge, with air quality expected to degrade
slowly this weekend as southwest winds transport smoke plumes from
source fires in eastern Washington and Oregon.

&&

.AVIATION...Scattered rain showers and isolated thunderstorms will
continue to stream over western Montana and north-central Idaho
through 14/1500Z this morning. Shower and thunderstorm activity
will redevelop this afternoon and evening, bringing a threat for
frequent lightning, brief heavy rainfall, and gusty, erratic winds
up to 35 kts to all aviation sites across the Northern Rockies.
However, KMSO, KHRF, KBTM, and KSMN will have the highest chance
for the strongest storms between 14/2000Z and 15/0200Z this
evening.

Persistent easterly winds have limited the impacts due to smoke
from regional and local wildfires, but this is likely to change
this weekend and early next week, when a southwest wind pattern
returns to the Northern Rockies.

&&

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

$$