Anaconda-Deer, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

866
FXUS65 KMSO 190939
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
339 AM MDT Thu Mar 19 2026

.DISCUSSION...

KEY MESSAGES:

- Rises in small streams and creeks through Friday for northwest
  Montana, especially Lincoln and Sanders counties

- Well above normal temperatures and gusty winds at times into
  Friday, especially I-90 southward

- More seasonable temperatures on Saturday with a cold front
  passage


An active moist southwesterly flow regime persists as an atmospheric
river (AR) remains pinned between a Gulf of Alaska trough and a
Desert Southwest ridge. The primary moisture plume continues to
favor northwest Montana and the Idaho Panhandle, keeping snow
levels elevated above 7000 feet. While the most intense forcing
has shifted northward, light precipitation will persist through
Friday morning before a secondary moisture surge brings a 30-50%
probability of >0.50 inch of rainfall to Lincoln and Sanders
Counties. This continued QPF, combined with high-elevation
snowmelt, will maintain rises on small streams and creeks, though
significant flooding is not currently anticipated.

Areas further south, generally south of Interstate 90, remain
entrenched in a record-breaking warm sector. Highs will reach the
upper 60s to low 70s across the Missoula and Bitterroot valleys,
with mid 70s to low 80s likely for the lower Salmon and Clearwater
River canyons. Record highs are specifically forecast for Butte
and Salmon through Friday. This thermal profile, combined with a
tightening surface pressure gradient, will support afternoon wind
gusts of 25 to 35 mph. The combination of warmth, gusty winds,
and low relative humidity will elevate fire weather concerns for
Lemhi County and southwest Montana through the end of the week.

A pattern transition occurs Saturday as a cold front traverses
the Northern Rockies, returning temperatures to seasonal
averages. While this front will trigger a period of gusty winds
and light, convective precipitation, overall impacts appear
minimal as the deeper moisture plume exits the region.


&&

.AVIATION...An active southwesterly flow regime will maintain VFR
conditions for most terminals today, though localized MVFR
ceilings and visibility remain possible across northwest Montana
and North-Central Idaho due to persistent light rain and low-level
moisture. The primary aviation concern focuses on a tightening
surface pressure gradient and deep mixing, which will generate
widespread west-to-southwest surface gusts of 25 to 35 kt this
afternoon, particularly for KMSO, KBTM, and KSMN. Strengthening
flow aloft interacting with complex terrain will also increase the
risk for mechanical turbulence and localized mountain wave
activity, especially along and downwind of the Bitterroot and
Sapphire ranges. While snow levels remain above 7,000 feet,
obscuration of higher terrain will continue across northwest
Montana through the evening.



&&

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

$$