FXUS65 KMSO 290638
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1238 AM MDT Sat Mar 29 2025

.DISCUSSION...


KEY MESSAGES:

- Snow impacts for southwest Montana and Lemhi County tonight into
  Sunday morning, especially at pass level.

- Active pattern with cool and showery weather most of next week.


An unsettled and showery pattern will dominate the weekend as an
upper-level trough moves across the Northern Rockies. A mid-level low will
track through southern Idaho into the Yellowstone region, bringing
widespread rain and snow to Lemhi County and southwest Montana by this
afternoon, continuing into Sunday morning.

*Travel Concerns: Snow impacts are likely for travel corridors
 around Butte and Anaconda late this evening into Sunday morning.
 Homestake, MacDonald, and Lost Trail passes, along with
 Georgetown Lake, have a 60-75% probability of receiving at least
 2 inches of snowfall. There is a 40-50% probability for Butte
 and Anaconda to see at least 2 inches as well. Southern Lemhi
 County, including Gilmore Summit, is also expected to see 2-4
 inches of snow. Travelers should allow extra time and be prepared
 for changing road conditions in these areas. Uncertainty remains
 regarding the exact strength and track of the mid-level low,
 which could affect snow amounts across southwest Montana and
 Lemhi County.

*Looking Ahead: An active pattern is highly likely (nearly 100% of
 ensemble models) next week, with periodic rain and snow across
 the Northern Rockies. Snow levels may occasionally drop to valley
 floors, but most impacts should remain at pass levels, leading to
 slick roads primarily during overnight and morning periods.

By around April 6th, about 90% of ensemble models indicate the
return of high-pressure ridging, bringing warmer and drier weather
to the region.



&&

.AVIATION...Patchy valley fog is a concern this morning, especially where
partial clearing has occurred. Otherwise, an unsettled and showery pattern
will take hold this weekend as an upper-level trough moves across the
Northern Rockies. A mid-level low will track through southern Idaho into
the Yellowstone region, bringing widespread rain and snow to Lemhi County
and southwest Montana by this evening, continuing into Sunday morning.

Mountain obscurations will be common, with lowered ceilings and reduced
visibility during periods of precipitation. Winds will generally remain
light, though a slight increase in northeasterly flow is expected south of
I-90 in western Montana.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch from late tonight through Sunday morning for
     Butte/Blackfoot Region.

ID...None.
&&

$$