Valier, Montana Weather Forecast Discussion

102
FXUS65 KTFX 301748
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
1148 AM MDT Tue Sep 30 2025
Aviation Section Updated.
.KEY MESSAGES...
- A very slow cooling trend will occur through the end of the
  work week.
- Scattered showers or a passing thunderstorm is possible over the
  next few days.
- A more significant cool down is expected this weekend, along
  with the potential for mountain snow Saturday night into Sunday.
&&
.UPDATE...
/Issued 808 AM MDT Tue Sep 30 2025/
Satellite imagery shows thickening cloud-cover spreading across
the area this morning ahead of the incoming upper level trough
approaching the west coast. An area of widespread showers/light
rain is lifting north across western MT, primarily affecting areas
along and west of the continental divide with some scattered
showers also lifting north into Southwest MT. Most of this shower
activity diminishes before reaching north-central MT with
somewhat better chances for showers there later this afternoon and
evening. Hoenisch
&&
.DISCUSSION...
/Issued 808 AM MDT Tue Sep 30 2025/
- Meteorological Overview:
An upper level trof is along the Pacific coast this morning. This
is creating a moist southwesterly flow aloft over the western half
of MT. As a result, scattered showers/isolated thunderstorms are
moving northward from ID into Southwest MT, with some of the
precipitation falling along the divide. That trend will continue
through today, with the precipitation slowly pushing eastward
towards Central MT later today. Some of the heavier showers could
produce around 0.20 inches of precip. For the next few days, the
weather pattern will remain similar, with the chances for
scattered showers continuing. Overall, no widespread significant
rainfall is expected through the rest of the work week.
In terms of temperatures, a very slow cooling trend will begin
today and then continue into the weekend. The cooling trend will
be slow/minor each day through Friday, but a more significant
cooling trend is expected this weekend, with afternoon
temperatures going below normal, especially on Sunday.
Over the weekend, the GFS/EC models continue to have separate
solutions on the weather pattern. One is dry, while one is
wet and cold. Overall the blend of two models is the current
forecast, resulting in scattered showers. Snow levels will lower
throughout the weekend, falling into the 6000 to 7000 foot range
by Sunday morning. Most of the accumulating snowfall will fall
along the Rocky Mountain Front, in the Kings Hill area, and then
in the mountains across Southwest MT.
This storm system should exit the area by Monday, with
warmer/drier air starting to move back into the CWA by next
Tuesday.
- Forecast Confidence & Scenarios:
The main concern will be the potential for accumulating snowfall
this weekend. Since the GFS/EC models are quite different, the
overall probability of a 4 inch snowfall is low. However, the
mountains around Big Sky and across Madison County look to be the
most favored areas right now for accumulating snowfall. Brusda
&&
.AVIATION...
30/18Z TAF Period.
South to southwesterly flow aloft will continues to spread
increasing mid level moisture and clouds across the region.
Widely scattered showers will affect mainly southwest MT through
this afternoon with an isolated weak thunderstorm possible as well
later this afternoon and evening. Brief MVFR visibility and
mountain obscuration will accompany showers at some SW MT
terminals with lower clouds near the ID border occasionaly
bringing MVFR ceilings and more widespread mountain obscuration
to the KWYS area. Breezy southwest winds developing early this
afternoon will diminish tonight but are likely to redevelop
Wednesday. Hoenisch
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  74  49  72  47 /  10  20   0  20
CTB  70  43  65  42 /  20  10   0  10
HLN  73  47  72  45 /  40  40  10  30
BZN  73  44  71  43 /  30  20  10  20
WYS  59  36  59  35 /  60  50  40  40
DLN  68  41  67  41 /  40  20   0  30
HVR  82  48  75  45 /  10  20   0  10
LWT  79  47  72  44 /  20  30   0  10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion