461
FXUS65 KMSO 150805
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
205 AM MDT Sun Sep 15 2024

.DISCUSSION...Satellite imagery early this morning shows a subtle
circulation over the coast of British Columbia near the U.S.
border. This feature is sending moisture into the Northern Rockies
from the southwest. Moist southwesterly flow will keep showers and
thunderstorms in the forecast through Monday while the
aforementioned circulation deepens over the West Coast.
Instability will increase on Monday, bringing chances for
thunderstorms up to about 30% for north-central Idaho and Montana
south of and along I-90. Threats from storms on Monday will
primarily be heavy rain and gusty outflow winds to about 40 mph.

The West Coast trough forms a closed low and moves into the Great
Basin on Monday night, pushing moisture into the Northern Rockies
from the south. Precipitation will become more widespread on
Tuesday and last through Wednesday as the low moves north.
Chances for a half inch of rain by Wednesday evening are more than
60% over the vast majority of the Northern Rockies. The lower
Salmon/Clearwater valleys, as well as the northwest corner of
Montana near Yaak will see a little less. The higher terrain along
the Continental Divide and the Clearwater range have about a
60-70 percent chance at an inch or more of precipitation. Two
inches will not be out of the question in the Swans, Flathead, and
along the Divide, especially in Glacier National Park.

Those recreating in the backcountry should be prepared for a wet
week with temperatures below normal and chances for snow above
about 8,000 feet. Most longer range ensemble solutions show
cooler, wetter weather to persist into next weekend.


&&

.AVIATION...A fast-moving disturbance will bring chances for
showers to most terminals later this morning and this afternoon.
Cloud cover will persist through Monday ahead of a significant
rain event midweek.


&&

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

$$