824
FXUS65 KMSO 161948
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
148 PM MDT Fri May 16 2025

.DISCUSSION...

KEY MESSAGES:

-  Wet system to bring moderate precipitation rates Saturday
   night into Sunday

-  Mountain pass level snow Saturday night and Sunday

-  10% chance for valley snow down to 3000 feet on Sunday

Little has changed in the forecast through Saturday. The primary
focus remains on the approaching low pressure system Saturday
night through Sunday.

Model guidance is converging on the storm track, with increasing
confidence in a lowering snow level and greater moisture
availability. Snow is likely to impact higher elevations,
including Lolo Pass, Lost Trail, and Gilmore Summit. Those
planning mountain travel or backcountry trips this weekend should
be prepared for winter-like conditions.

While this system doesnt show the same heavy snow signal as the
May 2024 storm, it could still produce wet snow capable of
breaking branches or damaging powerlines. Similar setups have a
tendency to drop snow levels lower than expected, bringing a low
(10-20%) chance of valley accumulations.

Snow impacts may linger along the Divide into Monday morning as
the system exits east.

With abundant moisture, patchy fog is possible Monday and Tuesday
mornings. A cool, showery pattern continues into Wednesday,
followed by a warming trend later next week.


&&

.AVIATION...Showers are expected at KGPI and KMSO this afternoon.
With showers in the vicinity of any terminal today there is a
potential for wind shift and gusts up to 20 kts. KGPI may again
have fog in the vicinity causing reductions in visibility or
ceilings after 17/0600z through 17/1400z.

A wet system is forecast to affect the Northern Rockies airspace
beginning around 18/0600z. All terminals are expected to
experience reduced ceilings and visibilities, with KMSO, KHRF,
KGPI, and KBTM potentially experiencing moderate to heavy
precipitation.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch from late Saturday night through Sunday
     afternoon for Bitterroot/Sapphire Mountains.

ID...Winter Storm Watch from late Saturday night through Sunday
     afternoon for Eastern Lemhi County...Southern Clearwater
     Mountains...Western Lemhi County.

&&

$$