018
FXUS65 KTFX 141141
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
541 AM MDT Tue Oct 14 2025

Aviation Section Updated.

.KEY MESSAGES...

- General cool, damp, and mostly cloudy conditions continue today with
  a few areas of passing light rain, snow, and or mixed
  precipitation expected.

- Another Pacific weather system will bring periods of rain
  showers and mountain snow Wednesday through early Friday,
  especially over southwest MT.

- Periods of breezy to windy conditions and mild temperatures are
  expected heading into the weekend.

&&

.DISCUSSION...
/Issued 355 AM MDT Tue Oct 14 2025/

 - Meteorological Overview:

The combination of mild and moist southwesterly flow overrunning
cold low level east to northeasterly flow has resulted in abundant
patchy fog, scattered areas of light snow, and even some
drizzle/freezing drizzle. This general pattern will continue over
the next couple of days, but gradually warming temperatures are
expected to limit the impacts from snow and freezing
precipitation. There may even be a few thunderstorms and or bursts
of heavier snow showers over the southwest this afternoon and
evening.

The elongated mid-level trough, responsible for the southwesterly
flow aloft, stretches southwestward into central CA where a
closed circulation will begin to swing northeastward through the
Great Basin and eventually into eastern MT by Thursday evening.
Most ensembles highlight this system merging with another trough
diving southeastward through BC/AB Thursday night into Friday.
This will bring the best chance for widespread lower elevation
rain and mountain snow Wednesday through early Friday. With milder
Pacific air moving in, snow impacts look to be on the minor side
and mostly confined to mountain areas. Most of the precipitation
is expected to fall east of a Dillon to Havre line and the primary
area of concern will be snow in the Madison and Gallatin mountain
ranges.

The Canadian trough merging on the back side of this system will
bring strong northwesterly flow aloft and breezy to windy
conditions Thursday night through Saturday before a brief period
of ridging for drier and milder conditions move in this weekend.
Another trough looks to move in late Sunday into early next week,
but the precise evolution of this system is uncertain at this
time. - RCG

 - Forecast Confidence & Scenarios:

Rain and snow Wednesday through early Friday...

The current path of the trough responsible for the rain and snow
expected Wednesday through Friday favors the most widespread
precipitation to fall mostly east of a Dillon to Havre line. These
areas currently have a 30 to 60% chance for rainfall/liquid
equivalent precipitation amounts exceeding a half inch for the 48
hour period ending Friday at 6 am, of course with mountain areas
boasting the greatest probabilities. Some deterministic models,
namely the NAM, have been bringing heavier precipitation and lower
elevation snowfall totals farther north into Central MT, but with
mid- and upper level temperatures running on the warm side,
generally around 0C at 700 mb, those solutions seem a bit
unrealistic. Snowfall probabilistic guidance also reflects the
warmer temperatures with only the Madison and Gallatin ranges
above 6,000 ft seeing a 50 to 70% chance for snow totals over 3
inches for the same 48 hour period ending at 6 am Friday. There is
also some uncertainty to sort out in regards of second trough
diving southeastward out of Canada being more influential and
shifting the precipitation even farther east than current
projections. This situation will be monitored in the coming days.
- RCG

&&

.AVIATION...
14/12Z TAF Period

Passing disturbances within a southwesterly flow aloft will
maintain scattered areas of rain, snow, and some mixed
precipitation for much of the TAF period. There will also be a few
thunderstorms in the southwest this afternoon. Expect periods of
widespread MVFR/IFR/LIFR conditions and mountain obscuration due
to low stratus, patchy fog, and or rain/snow. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  29  46  34 /  20  20  30  40
CTB  39  23  49  29 /  20  20  10  20
HLN  42  29  45  33 /  20  40  50  50
BZN  48  30  48  31 /  40  60  60  70
WYS  52  28  46  27 /  60  80  90  80
DLN  47  32  48  32 /  50  50  60  60
HVR  46  30  50  35 /  20  20  40  50
LWT  46  29  47  33 /  20  40  50  70

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$
http://www.weather.gov/greatfalls