459
FXUS65 KMSO 280954
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
354 AM MDT Sat Jun 28 2025

.DISCUSSION...


KEY MESSAGES:

-  Isolated to scattered showers and thunderstorms along the
   Canadian border this afternoon/evening

- Warming and drying trend Sunday into early next week, with
  temperatures 10-15F above normal.

- Shower and thunderstorm activity returns Tuesday, becoming more
  widespread, especially along and south of I-90.

A low amplitude trough will continue to be over the Northern
Rockies today keeping temperatures near seasonal readings. HiRes
models are indicating some isolated showers moving through
northwest Montana this morning. Then the coverage and intensity of
the convection increasing during the afternoon with the main focus
being along the Canadian border.

A ridge of high pressure builds over the region Sunday into the
first part of next week causing very warm and dry conditions.
Temperatures will be running 10 to 15 degrees above seasonal
averages, as the valleys experience upper 80s to mid 90s by Monday
afternoon. The lower valleys of north central Idaho are expected
to have temperatures breaking into the triple digits.

Showers and thunderstorms return Tuesday next week, with activity
becoming more widespread Wednesday under a south-southwest flow
pattern. Ensemble guidance has been consistent the last few days
highlighting a surge of subtropical moisture across the Great
Basin into the Northern Rockies, with atmospheric moisture
climbing 125-150% of normal by Wednesday. This flow pattern will
be aided by a ridge of high pressure centered near the Four
Corners region and a closed low forming over California, seen
within deterministic runs of the 12z GFS/ECMWF. A deeper dive into
instability suggests the potential for a few stronger
thunderstorms capable of producing heavy rain and small hail given
the anomalously high atmospheric moisture. The lack of an
organized mid-upper level jet will limit wind shear and the
potential for organized long-lived severe convection.

&&

.AVIATION...A few light showers will continue to move through
northwest Montana this morning. These showers are anticipated to
stay north of KGPI. This afternoon the convection will increase in
coverage and intensity, but the main area of focus will remain
along the Canadian border. A mid level cloud deck along with gusty
northwest winds this afternoon will be affecting the remainder of
the terminals today.

&&

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

$$