924
FXUS65 KMSO 101847
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1247 PM MDT Sun May 10 2026

.DISCUSSION...

KEY MESSAGES:

-  Hot and dry weather through Wednesday, with temperatures
   reaching into the mid 80s to low 90s by Tuesday and Wednesday.

-  Spring thunderstorms Wednesday and Thursday; main hazards will
   be lightning and erratic/gusty outflow winds.

-  Weekend Cool Down, but near seasonable levels.

An area of high pressure will bring an early taste of summer to
the Northern Rockies this week. A weak weather system passing
near the Canadian border tonight will introduce mid to high-level
clouds and breezy conditions through Monday, providing minor
relief from the heat for most locations. However, southern areas
of our region, such as Salmon, will remain unseasonably warm with
highs in the mid-80s. Temperatures will peak Tuesday into
Wednesday as the high pressure strengthens, bringing near-record
heat. There is a 50 to 60 percent chance that some lower valleys
in western Montana will reach 90 degrees on Wednesday, with some
locations within a degree or two of the daily record high
temperatures. This rapid warm-up will accelerate high-elevation
snowmelt, leading to steady rises on area rivers. Outdoor
recreationists should exercise extreme caution, as local waterways
will be running very fast and dangerously cold.

As the week progresses, changing weather conditions will introduce
new hazards. Breezy and dry conditions developing across
southwest Montana on Wednesday afternoon will lead to elevated
fire weather concerns. Concurrently, the overall weather pattern
will begin to shift, bringing a threat of spring thunderstorms
capable of producing lightning and gusty winds from Wednesday
afternoon through Thursday. Looking toward the end of the week,
forecast models indicate a potential for a significant pattern
change. Considerable uncertainty remains regarding the exact
timing and evolution of this change, with current guidance split
between extending the warm weather or introducing a much cooler
and wetter system to the region.

&&

.AVIATION...VFR conditions will prevail across the Northern Rockies
airspace through the forecast period under the influence of a
building upper-level ridge. A weak shortwave passing near the
Canadian border tonight into Monday will bring passing mid to
high-level clouds and localized showers, primarily impacting
northern terminals like KGPI, though ceilings will remain firmly
VFR. This feature will also yield breezy surface winds across the
region through Monday with gusts of 20 to 25 knots, which may
introduce localized mechanical turbulence. Aside from the winds,
the primary operational impact will be steadily increasing density
altitudes as early-season heat develops, remaining a persistent
concern into mid week.

&&

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

$$