195
FXUS65 KMSO 161733
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1133 AM MDT Wed Sep 16 2026

.DISCUSSION...


KEY MESSAGES:

-  Warm and dry today with sunny skies; breezy easterly winds
   developing this evening.

-  Showers and thunderstorms Thursday into Friday, generally south
   of Highway 12 and I-90. Storms will be capable of brief heavy
   rain, small hail, and sudden wind gusts up to 45 mph.

-  Another warming and drying trend Sunday through early next
   week.

A brief area of high pressure over the region today will bring pleasant,
sunny, and near-normal temperatures, with highs reaching the 70s in western
Montana and the 80s in Idaho. Northeast winds of 10 to 15 mph with gusts
around 20 mph will develop this afternoon. After sunset, winds will
increase, bringing easterly wind gusts over 20 to 25 mph, particularly in
narrow valleys along and west of the Continental Divide and along the
eastern shores of Flathead Lake.

A low-pressure system will approach southwest Idaho on Thursday, drawing a
surge of monsoon moisture into the area. Combined with strong wind shear
(changing wind speeds and direction with height), this system
will trigger thunderstorms capable of producing heavy rain,
lightning, gusty winds, and small hail. On Friday, afternoon
heating could increase instability once again, elevating the
threat for strong storms capable of producing larger hail (around
1 inch in size). The highest chances for these thunderstorms will
focus across central Idaho and west-central to southwest Montana,
northwest Montana will experience much lower chances for
thunderstorms, though a few showers are possible. While northwest
Montana will largely miss out on the activity, sudden wind gusts
from the storms much further south are expected to move into the
Mission and Flathead valleys Thursday evening and Friday. If you
have plans to be on Flathead, Swan, or Seeley lakes, expect to
experience sudden gusty winds out of the south after 8 PM.

As the low-pressure system exits the region on Saturday, the focus for
showers and thunderstorms will shift east of the US-93 corridor into
central Montana, leaving the lower valleys of Idaho mostly dry with warming
temperatures. High pressure will then build across the region from Sunday
into early next week. Expect patchy morning fog in river valleys followed
by afternoon highs potentially reaching the 80s in Missoula and the lower
valleys of Idaho. There will also be increasing chances for morning frost
by mid-week through this weekend. By mid-week, there remains around a 50
percent chance that a passing cold front could bring breezy conditions and
cool down the early-week warmth.


&&

.AVIATION...High pressure will maintain VFR weather conditions
through tonight into Thursday morning. Localized breezy easterly
canyon and downsloping winds will pick up this evening into the
overnight. Mid-level clouds begin to increase by mid-day Thursday
with thunderstorms developing primarily after 17/1800z.
Thunderstorms Thursday afternoon will be capable of localized
intense rainfall periodically reducing visibility, hail up to one
inch in diameter, and strong outflow wind gusts of 30 to 40
knots.

&&

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

$$