874
FXUS65 KMSO 061853
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1253 PM MDT Mon May 6 2024

.DISCUSSION...A low pressure system moving through central and
eastern Montana will maintain cool, wet and breezy conditions over
western Montana and north central Idaho through Wednesday. The
two main concerns with this pattern will be for higher elevation
snow and strong winds, detailed below.

High elevation snow:  Precipitation will become widespread over
western Montana and north central Idaho once again during the day
Tuesday, lasting into Wednesday.  Snow levels will lower to roughly
4000 feet by early Wednesday morning, resulting in some hefty
snowfall totals in the terrain, especially above 5000 feet along the
Continental Divide. Forecast models show a 50 to 60 percent chance
of 6" of snow or more for locations such as Marias Pass, Georgetown
Lake, MacDonald Pass and Homestake Pass. Even the high valleys of
southwest Montana (Butte, Anaconda, Philipsburg) will see snowfall,
with a 70 to 80 percent chance of seeing 2" of snow by mid day
Wednesday. Winter Weather Advisories have been issued for the
Glacier National Park and Butte/Blackfoot regions to account for
snow travel and slick roads.

Winds:  Breezy winds are already evident this afternoon, with gusts
up to 40 mph possible through early this evening.  Winds will
decrease for most locations overnight, but become breezy once again
Tuesday morning.  The strongest winds are expected to be focused
over the higher terrain along the Continental Divide and into
southwest Montana along the Highway 12 corridor from Garrison
Junction to MacDonald Pass and Interstate 90 from Drummond to
Homestake Pass.  Gusts to 55 mph in these areas could cause minor
tree damage and make travel difficult for high profile vehicles.
In addition, Flathead Lake will see breezy winds with gusts up to
near 40 mph, causing choppy water conditions for small craft. Wind
highlights have been issued to address these concerns. Winds are
expected to decrease by late Tuesday evening for valley locations.
However, breezy winds with gusts to 30 mph will likely continue
in the terrain and may combine with snow to cause locally lowered
visibility into Wednesday morning, especially for MacDonald and
Marias Passes.

For Thursday into early next week, the majority of forecast models
(70 percent) point to an overall dry and warm weather pattern as
high pressure builds in from the west.  The other 30 percent of
models show a closed low pressure system moving just to the south of
the region, which would lead to showers and a less robust warm up.
If the 70 percent of model solutions is correct, temperatures would
warm into the upper 70s and low 80s for most valley locations by
Mother`s Day!

&&

.AVIATION...A cool, wet, and windy weather pattern will remain in
place across the Northern Rockies through the next 36 hours. This
will keep periodic showers and lower ceilings in place across the
area and at most airfields. Conditions will gradually deteriorate
tonight as a secondary shortwave trough rotates through the
region. The snow level will lower to around 4000 feet by Tuesday
night with accumulations, along with reduced visibility and
significantly lowered ceiling heights, expected at KBTM. Breezy
winds are also likely throughout the Northern Rockies with gusts
to 30 knots possible during the afternoon at KGPI, KMSO, and KBTM.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 6 PM Tuesday to 11 AM MDT Wednesday
     for West Glacier Region above 4000 feet.

     Lake Wind Advisory from 9 AM to 8 PM MDT Tuesday for
     Flathead/Mission Valleys.

     Wind Advisory from 6 AM to 9 PM MDT Tuesday for Butte/Blackfoot
     Region.

     Winter Weather Advisory from 9 PM Tuesday to 11 AM MDT Wednesday
     for Butte/Blackfoot Region.

ID...None.
&&

$$