633
FXUS65 KMSO 210948
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
348 AM MDT Tue May 21 2024

.DISCUSSION...A subtle ridge of high pressure will slide over the
Northern Rockies today causing a slight warming trend, but
scattered showers will continue to affect portions of the region.

A strong low pressure system will track across the region
Wednesday through Thursday. The far majority of the models have
the center of the low pressure system slide southward into
southern Idaho before lifting to the northeast across Yellowstone
into eastern Montana. The track of the system will bring
widespread precipitation to the Northern Rockies with the high
probability of hefty snow across Lemhi county into southwest
Montana. The latest model runs are showing a 70 to 90 percent
chance of greater than 4 inches of snow by Thursday morning for
Lost Trail, Georgetown lake and Homestake pass. Lost Trail and
Georgetown Lake even have a 40-60% chance of more than 8 inches of
snow during this event. Snow levels are now expected to be low
enough that Butte should receive accumulating snow by Thursday
morning.

All the model clusters are showing a secondary low pressure system
sliding through the Northern Rockies on Saturday once again
bringing widespread precipitation. Around 46% of the models are
showing a similar track for the low pressure system as the
Wed/Thur storm, meaning that Lemhi and southwest Montana could
receive another round of significant snow.

A ridge of high pressure will be building over the Northern
Rockies during the first part of next week causing a warming and
drying trend.


&&

.AVIATION...A subtle ridge of high pressure is moving over the
region today. The combination of partly cloudy skies along with
moist low levels from yesterday`s precipitation has allowed for
the development of patchy fog and low stratus. KGPI and KMSO are
the two terminals that will be mainly impacted by the fog and
stratus this morning. Even though a ridge is over the region
isolated to scattered showers will be moving through causing short
periods of reduced visibility.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch from Wednesday evening through Thursday
     morning for Bitterroot/Sapphire Mountains...Butte/Blackfoot
     Region.

ID...Winter Storm Watch from Wednesday evening through Thursday
     morning for Eastern Lemhi County...Western Lemhi County.

&&

$$