270
FXUS65 KMSO 251920
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
120 PM MDT Sat May 25 2024

.DISCUSSION...Shower activity will continue across the Northern
Rockies through this evening into Sunday morning as a Pacific
trough moves across the region. GOES Day Cloud imagery points
towards a destabilizing atmosphere as evident by colder cloud
tops and glaciating ice associated with showers. The best axis of
instability will set up along the divide, where the HREF paints a
a 15-20% probability for thunderstorms from 300-700pm MDT.

High pressure will begin to build across the Northern Rockies
Sunday, with a significant warming trend by Monday and Tuesday
next week. Shallow moisture and instability will keep showers
going across the terrain in northwest Montana Sunday. Confidence
is high for temperatures to reach into the 80s Tuesday, with
probabilities reaching 70-80% for valleys in western MT and
central ID. The lowest valleys in Idaho and Clearwater County may
even manage the 90 degree mark.

The threat for organized thunderstorms increases Tuesday afternoon
and evening. Forecast models suggest a Pacific trough will move
onshore in OR/WA with southwesterly flow transporting an axis of
instability across the Northern Rockies. Ensemble guidance,
suggests the best axis of instability and shear will set up across
the Camas Prairie of Idaho and along the ID/MT border. Instability
(100-500 J/kg) and wind shear profiles (35-45kts) suggest storms
may organize into multicellular line segments, with outflow winds
and brief heavy rain being the primary storms threats.

Forecast confidence decreases Wednesday into Thursday next week.
Guidance is struggling with the amplitude and track of the
aforementioned Pacific trough as it moves eastward. Roughly 40% of
solutions suggest the trough will deepen into a closed low, with
widespread precipitation and another round of snow across
southwest MT and the higher elevations in ID, while the other
members portray a weaker trough with higher snow levels and less
precipitation. By Thursday, ensemble probabilities for 1" or more
of snow reach 30-40% above 5,000 feet across central ID and
southwest MT. /Lukinbeal

&&

.AVIATION...Shower activity will continue across the Northern
Rockies airspace through this evening into early Sunday morning as
a Pacific trough moves into eastern MT. The atmosphere will
continue to destabilize, with the best axis of instability setting
up along the divide, where probabilities for thunderstorms hit
15-20% from 25/2000Z to 26/01000Z. /Lukinbeal

&&

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

$$