Polebridge, Montana Weather Forecast Discussion

795
FXUS65 KMSO 280902
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
302 AM MDT Sun Sep 28 2025
.DISCUSSION...
KEY MESSAGES:
- Unseasonably hot and dry conditions today with hazy skies from
  wildfire smoke
- Thunderstorms capable of gusty outflow winds up to 50 mph on
  Monday, mainly south of Interstate 90
- Cooler and wetter by Tuesday into the weekend
An upper-level ridge of high pressure will bring one more day of
unseasonably warm and dry conditions, with today being the hottest
day of the forecast period. Valley temperatures will reach into
the low 80s, with some lower valleys in north-central Idaho
approaching 90 degrees. Wildfire smoke present across northwest
Montana is expected to see some improvement this afternoon and
evening as transport winds shift.
A significant pattern change will begin Monday as a Pacific trough
approaches from the west. Initially, increasing moisture aloft
over a dry low-level airmass will support the development of
high- based thunderstorms Monday afternoon and evening. Stronger
storms will be capable of producing outflow winds up to 50 mph.
The threat will then transition through Monday night as the lower
levels moisten.
By Tuesday, a much deeper moisture profile will lead to widespread
showers and the potential for more efficient, heavy rain-
producing thunderstorms. All of western Montana and north central
Idaho have a 70 to 90 percent chance of receiving wetting rains
(>0.10"). Probabilities for receiving 0.25" or more are highest in
north-central Idaho (around 70%) and range from 30 to 50 percent
across western Montana. Embedded convection could produce locally
intense rainfall rates of 0.50" per hour or more, elevating the
risk for excessive runoff and debris flows, particularly over
steep terrain and recent burn scars.
Model guidance has trended significantly cooler and wetter for
the extended forecast, with a strong consensus for an upper
trough to impact the region late next week and into the weekend.
While confidence in this general pattern is high, considerable
uncertainty remains regarding the trough`s specific evolution.
Scenarios from ensemble clusters range from a progressive
shortwave trough bringing periodic precipitation, to a deeper,
slower-moving cutoff low that would result in more prolonged,
significant precipitation and potential for mountain snowfall.
Specifics on precipitation timing and amounts will become clearer
in subsequent forecast cycles.
&&
.AVIATION...High pressure will maintain generally clear skies, warm
daytime temperatures and light/terrain driven winds through
tonight. Wildfire smoke will cause hazy skies and may locally
lower visibility at times, particularly across northwest Montana
this morning. As transport winds aloft shift this afternoon, some
improvement is possible.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$

NWS MSO Office Area Forecast Discussion