FXUS65 KMSO 131916
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
116 PM MDT Sat Jun 13 2026

.DISCUSSION...

KEY MESSAGES:

-  High pressure this weekend into early next week bringing
   warming trend, with 80s for western Montana and mid-upper 90s
   for central Idaho.

-  West-northwest flow pattern by middle of next week, opening the
   door for periodic disturbances, showers, and thunderstorms.

Satellite images this afternoon shows shallow cumulus clouds
developing along the Continental Divide and the higher terrain of
western Montana. Forecast soundings point towards mid-level
instability increasing along the divide by mid-late afternoon,
setting the stage for isolated shower activity across the higher
terrain. By this evening, an easterly pressure gradient will
increase, with east-northeast wind gusts of 15-25 mph across
western Montana valley areas around sunset through midnight.

Model ensembles are in strong agreement (90% confidence in cluster
analysis) for high pressure to build and shift inland along the
Pacific Northwest this weekend into early next week. This leaves
the Northern Rockies positioned under west-northwest flow aloft
with strong subsidence and warming to our west. Valley
temperatures will reach into the upper-70s and 80s across western
Montana. Extreme low elevation river valleys of central Idaho
will push into the mid- to-upper 90s by Tuesday.

The flow becomes northwesterly by Tuesday and Wednesday. This
will bring windy conditions to the region as a shortwave trough
moves along the Canadian border in northwest Montana. Confidence
has increased for wind gusts greater than 30 mph Tuesday afternoon
across western Montana valleys, with probabilities reaching
70-90%. Those with outdoor recreation plans should monitor the
forecast closely especially for area lakes and the higher
terrain. The strongest gusts (50-60 mph) will focus across the
Bitterroot Crest and mountain ranges along the Continental Divide.
Furthermore, the combination of warm, dry, and windy conditions
will bring elevated fire weather concerns along and east of the
divide in southwest Montana.

As discussed previously, forecast uncertainty begins to increase
by Thursday and Friday of next week. Despite this, it appears
that temperatures will generally stay above average. Ensemble
cluster analysis suggests a slight chance (15-20% probability) for
upper level disturbances to bring showers and a few
thunderstorms. Around 50 percent of the ensemble model clusters
depict a deeper trough over the Pacific Northwest by Friday. This
type of pattern could support strong thunderstorms heading into
next weekend.

&&

.AVIATION...A north-northeast gradient has developed across the
Northern Rockies this afternoon, with high pressure east of the
divide. Shallow moisture and instability is leading to cumulus
clouds along the divide and mountain areas of western Montana.
High-resolution guidance along with forecast soundings suggest
isolated shower activity across the divide by mid-afternoon
through early evening. Showers will struggle to move off the
terrain, with valley areas staying mostly dry. Winds will become
east-northeast around sunset through midnight, with gusts reaching
15-20kts along the divide.

&&

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

$$