577
FXUS65 KMSO 280809
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
209 AM MDT Sun Apr 28 2024

.DISCUSSION...Low pressure spinning over the Gulf of Alaska is
pushing Pacific moisture into the northwestern U.S. this morning
while another low departs the Rocky Mountain West and enters the
Great Plains. The Northern Rockies will be between these systems
for a short period of time today. Southwest Montana and Lemhi
County will get a short break in precipitation while the Pacific
system moves closer. In the meantime, northwest Montana, along
with Clearwater and Idaho Counties, will see continued
precipitation in the form of lower elevation rain and high
elevation (above about 5000 ft) snow today. A cold front
associated with this system will bring some increasing westerly or
southwesterly winds this afternoon ahead of the frontal passage.

By Monday, the low will arrive in the Pacific Northwest.
Continued frontal dynamics, along with Pacific moisture and a
favorable position of the upper level jet will result in moderate
precipitation focused on north-central Idaho and the southern
Bitterroot Valley. Snow levels will lower to around 3800-4500 feet
in these locations. Locations like Elk City, Dixie, Lolo Pass, and
Lost Trail Pass could receive 1 to 3 inches of wet snow, while
higher elevations of the Clearwater, Bitterroot, Anaconda, and
Pintler Mountains could receive 6 to 12 inches of snow.

The unsettled and cool pattern continues through the first week
of May. Tuesday through Wednesday, a back door cold front will
affect the Continental Divide as a closed low forms on the east
side. Wraparound moisture from this system will be conducive to a
spring snow event for the Glacier Park region and the Divide to
include Marias Pass, where there is about a 50% chance of seeing 4
or more inches of snow by Wednesday evening.


&&

.AVIATION...A break in shower activity this morning will make fog
a good possibility at KMSO. Otherwise, expect a mostly overcast
day with decreasing shower activity and increasing westerly or
southwesterly winds with gust to about 20 kts this afternoon.
Showers will become more widespread again tonight, especially over
the terrain along the Idaho-Montana border.



&&

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

$$