898
FXUS65 KMSO 291003
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
403 AM MDT Sun Jun 29 2025

.DISCUSSION...

KEY MESSAGES:

- Warming and drying trend Sunday into early next week, with
  temperatures 10-15F above normal.

- Moderate risk of heat impacts across low elevations of Idaho
  and Clearwater Counties Monday and Tuesday.

- Shower and thunderstorm activity returns Tuesday, becoming more
  widespread into Wednesday.

Ridge of high pressure will be building over the region the next
couple of days causing a warming and drying trend. Temperatures
will be reaching 10 to 15 degrees above seasonal averages. The
combination of extremely warm afternoon temperatures along with
mild nights in the lower valleys of Clearwater and Idaho counties
will create potentially dangerous heat stress so a heat advisory
has been issued for Monday afternoon through Tuesday evening.

Some monsoonal moisture appears to make its way up into Lemhi
county and southwest Montana on Tuesday afternoon. This moisture
combined with afternoon instability will kick off a few high based
showers and thunderstorms. Any storms that develop during this
time could produce gusty erratic winds. Then on Wednesday the
upper level flow will become southwesterly as a weak cold front
pushes through the Northern Rockies. The cold front along with
increased monsoonal moisture will potential create an environment
of the development of widespread convection Wednesday afternoon. A
few of these storms could become strong enough to produce heavy
rain, small hail and strong outflow winds.

The consensus of the models indicate that the Northern Rockies
will remain under southwesterly to westerly flow through the
remainder of the work week into the holiday weekend. This pattern
will be conducive to afternoon/evening showers and thunderstorms
along with temperatures remaining 5 to 10 degrees above seasonal
averages.


&&

.AVIATION...A ridge of high pressure will be building over the
region for the next couple of days creating fair flying
conditions. The only impact to the aviation community will be some
mid-level clouds lingering along the Continental Divide near
Glacier NP and Bob Marshall wilderness.

&&

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

&&

$$