FXUS65 KMSO 051005
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
405 AM MDT Sun Apr 5 2026

.DISCUSSION...

KEY MESSAGES:

-  Warming trend through Monday under high pressure

-  Strong, potentially damaging winds Tuesday: Confidence is
   growing for significant impacts across western Montana. High
   Wind Watches may be required.

-  Unsettled next weekend: Precipitation chances return Saturday
   and Sunday.

Short-Term(Through Monday Night):
High pressure remains the dominant feature. Expect highs in the
60s and 70s by Monday. This evening, an easterly wind will develop
over the Divide and west. Gaps and channeled terrain could
experienced 15 to 30 mph, which could create hazardous conditions
for small craft on Swan Lake, McDonald Lake and Yellow Bay.


Mid-Term(Tuesday through Thursday):
The forecast has trended more aggressive regarding wind potential.
A deep surface low over the Canadian Prairies will sweep a dynamic
cold front through the Northern Rockies. The ECMWF Extreme
Forecast Index (EFI) is highlighting west-central and northwest
Montana for anomalously high wind speeds, suggesting the potential
for damaging gusts.

The latest NBM 5.0 guidance and high-resolution WRF modeling show
a sharp increase in probabilities for significant wind at select
locations:

- Probabilities of gusts greater than 52 mph: 70-85% for the west-
  central Bitterroot Valley, Anaconda, MacDonald Pass, I-15 south
  of Butte, and Hot Springs. Ashley Lake area sits at 80% with
  Salmon and Kila around 60%.

- Probabilities of gusts greater than 63 mph: 50-72% from Victor
  to Hamilton and Anaconda; 47% for Stevensville.

- Peak Potential: High-res WRF and NBM indicate a 50% chance for
  gusts exceeding 70 mph between Stevensville and Hamilton,
  specifically west of US-93.

Given these trends, High Wind Watches may be necessary as the
event nears. Behind the front, much cooler air settles in, with
widespread sub-freezing morning lows expected Wednesday through
Saturday.

Long-term(Friday into next weekend):
Brief ridging on Friday gives way to an increasingly active
pattern. The NBM has introduced precipitation chances for
Saturday, primarily south of Missoula. By Sunday, April 12th, the
chance for widespread precipitation increases. Around 74% of the
ensemble clusters depict an unsettled, long-wave trough pattern
during this timeframe.

&&

.AVIATION...Mid to high cloud cover will increase west to east
this morning. A high pressure ridge will keep VFR conditions going
through Monday.


&&

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

$$