635
FXUS65 KMSO 112039
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
239 PM MDT Fri Jul 11 2025

.DISCUSSION...

KEY MESSAGES:

- Warming trend Friday into the weekend, with moderate heat risk
  impacts across low elevations of north-central Idaho

- A big change is possible across the region later Monday into
  Tuesday with winter-like conditions possible along the Divide,
  especially Glacier National Park with northeast winds.

A ridge of high pressure over the Pacific Coast Saturday will
shift eastwards over our region by Sunday. This will turn up the
heat, especially for lower elevations of north-central Idaho. With
highs in the low 100s and warm overnight temperatures, we hoisted
heat advisories for the area between Orofino, Camas Prairie, Hells
Canyon and Salmon River Valley. Make sure you drink plenty of
fluids, stay out of the sun, and schedule frequent rest breaks in
shaded or air conditioned environments.

If you are planning on recreating in the backcountry later Monday
into Tuesday, you will want to read the following. A relatively
rare low pressure system will drop out of British Columbia during
this period.

Cold & wet conditions: The highest probabilities for rainfall
exist across western Montana, especially over Glacier National
Park. Easterly winds will make the temperatures in the 40s feel
much colder along with the rain!

Easterly winds: If the cold front from Canada arrives sooner on
Monday, then there could be stronger easterly winds that develop
in the valleys. This is one of those events that old-timers
around Flathead Lake talk about...a sudden wind shift that could
catch boaters off-guard.

Possible mountain snow: Snow levels right now are forecast at
8,000 feet MSL in Glacier National Park, but could be lower if
the storm becomes stronger than forecast.

Once this storm system moves off to the east by mid-week, night-
time low temperatures could get down into the upper 20s and 30s
for high valleys.


&&

.AVIATION...A warm-up, along with VFR conditions are expected
through the weekend. With temps in the 90s and low 100s(lower
elevations of central Idaho), density altitude could become a
concern. Expect longer takeoff rolls and reduced climb
performance in the afternoons. The upper ridge axis will be
positioned to the west of the region Saturday, so there could be
slightly higher localized winds at GPI and along the Divide.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Heat Advisory from noon Saturday to 8 PM PDT Monday for Lower
     Hells Canyon/Salmon River Region...Orofino/Grangeville
     Region.

&&

$$