Sun River, Montana Weather Forecast Discussion

760
FXUS65 KTFX 010253
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
853 PM MDT Tue Sep 30 2025
.KEY MESSAGES...
- Another round of scattered showers and isolated thunderstorms
  this afternoon/evening.
- Breezy southwest to west winds today and Wednesday.
- A cooling trend through the weekend, with the weekend system
  bringing mountain snow.
&&
.UPDATE...
With just some light rain across the area, the forecast remains
largely on track. Therefore, no changes are needed to the existing
forecast. Ludwig
&&
.DISCUSSION...
/Issued 604 PM MDT Tue Sep 30 2025/
- Meteorological Overview:
An occluding low out along the Pacific coast will keep this
troughing pattern through the week and beginning of next week.
Today, an embedded upper level wave will bring scattered showers
and isolated thunderstorms this afternoon. Weak CAPE will keep
thunderstorms isolated and weak. Stronger mid level winds from
this occluding low will keep breezy to windy conditions today and
Wednesday. The strongest winds are more concentrated in Southwest
MT in the north to south orientated valleys and along the Rocky
Mountian Front. Precipitation will be more isolated Wednesday.
This closed upper level wave does look to open up a bit as it
enters the interior Northwest U.S Thursday and Friday. Coverage in
precipitation increases across Southwest and Central MT as the
trough axis propagates farther east across the Northwest U.S.
The cold front passing through today will help initiate the
general cooling trend through the weekend. Models hint at another
wave coming from British Columbia Saturday and Sunday. There still
remains some variability in the track of this wave, and as a
result, precipitation amounts remain uncertain. Snow levels are
expected to drop Friday through Monday. The "middle ground" model
solution show snow levels cooling to 6,000-7,000ft in Southwest MT
Sunday morning, and closer to 5,000ft towards the Canadian
border.
- Forecast Confidence & Scenarios:
There still are varying amounts of precipitation and mountian
snow with the weekend system with different solutions of the track
of the upper-level wave. The 25th percentile (lower end amounts)
of precipitation amounts range up to 0.20" of an inch in Southwest
MT, to no precipitation in North Central MT. The 75th percentile
ranges from 0.30"-0.80" across Southwest MT and 0.10-0.30" across
North Central MT.
In terms of mountain snow, there`s a 20-40% chance for 1" of
snow, up to a 20% chance for 4" of snow in Central MT and the
Continental Divide, and a 10-30% chance for 4" of snow in the
Gallatin Range.
Low temperatures Monday morning look to drop near or at freezing
temperatures across lower elevations. There`s a 50-90% chance for
Monday morning temperatures dropping to at least 32 degrees.
-Wilson
&&
.AVIATION...
00/00Z TAF Period.
While VFR conditions are expected to prevail across North Central
and Southwestern Montana, even as southwesterly flow brings
increasing moisture into the area. A few SHRA and isolated TSRA
are expected this evening that could bring some brief MVFR vis and
ceilings, but these should dissipate by 6z. Some gusty winds are
also expected across SW MT this evening, with winds shifting to
the plains tomorrow afternoon. Ludwig
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  49  72  45  72 /  30   0  10   0
CTB  43  65  41  65 /  10  10  10   0
HLN  48  72  46  71 /  50  10  10  20
BZN  44  71  43  69 /  20  10  10  40
WYS  35  58  33  63 /  50  30  10  50
DLN  41  67  41  65 /  30  10  10  30
HVR  48  73  44  73 /  10  10   0   0
LWT  47  72  45  71 /  30  10   0  10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion