048
FXUS65 KTFX 201111
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
411 AM MST Sat Dec 20 2025

Aviation Section Updated.

.KEY MESSAGES...

- Periods of mountain snow this weekend and next week, mostly
  along the Rocky Mountain Front and over the higher terrain of
  southwest Montana.

- Near to above average temperatures are generally expected, but
  Arctic air will periodically clip northern areas.

&&

.DISCUSSION...
/Issued 305 AM MST Sat Dec 20 2025/

 - Meteorological Overview:

Flat ridging aloft moves over the Northern Rockies today and
tonight for drier and breezy conditions. Moisture streaming
towards the Continental Divide will be sufficient for continued
snow along the immediate eastern slopes of the Rocky Mountain
Front.

The next Pacific trough moves in Sunday into Monday and brings
more mountain snow, along with another shot of Arctic air over the
plains. Snow with this system looks to be on the lighter side and
mostly confined to the higher terrain along the Rocky Mountain
Front and over the southwest MT.

Southwesterly flow aloft develops Tuesday through next weekend
with a series of shortwaves/troughs bringing periods of mostly
mountain snow and breezy to windy conditions. Arctic air taking up
residence just north of of the Canadian border will occasionally
spill southward onto the plains. - RCG

 - Forecast Confidence & Scenarios:

Periods of mountain snow this weekend and next week...

While most locations dry out today and tonight, moisture
streaming over the Continental Divide will maintain light snow
along the higher terrain of the Rocky Mountain Front. The current
winter weather advisory highlighting an additional 2 to 5 inches
of snow near the Marias Pass area still looks good.

The next shortwave trough approaches from the southwest on Sunday
and initially brings a couple rounds of precipitation to central
and southwestern MT. Accumulating snow will mostly be confined to
the higher terrain south of I90 where there is 60 to 80% chance
for 3 inches of snow or greater over the Pioneer, Beaverhead, and
the Gallatin/Madison Mountains Sunday into Monday. Snow returns to
the Rocky Mountain Front by Monday with similar probabilities for
3 inches of snow or more. A series of shortwaves/troughs then
bring more opportunities for mostly mountain snow and breezy to
windy conditions for the second half of next week. - RCG

&&

.AVIATION...
20/12Z TAF Period

VFR conditions are generally expected for the TAF period; however,
there will be ongoing snow and mountain obscuration over the
higher terrain along the Continental Divide. Some of this moisture
may stream eastward into the plains and valleys for brief low
VFR/MVFR conditions in clouds and or light snow through 20/18Z,
mostly along the Hi-Line. Gusty southwesterly winds develop over
central and north-central MT today with gusts mostly staying in
the 20 to 30 kt range. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  27  42  31 /   0   0   0  20
CTB  35  23  37  21 /  30   0   0  10
HLN  38  22  38  28 /  10   0  10  50
BZN  37  19  40  31 /   0   0  30  50
WYS  27  14  36  29 /  10  30 100 100
DLN  34  19  39  31 /   0   0  30  60
HVR  25  19  37  18 /  20   0   0  10
LWT  36  24  40  29 /   0   0  20  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST this afternoon for East
Glacier Park Region-Southern Rocky Mountain Front.

&&

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