textproduct: Great Falls

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.

UPDATE

The current forecast remains on track with minor snow accumulations continuing throughout the day along the Rocky Mountain Front. The current Winter Weather Advisory along there remains on track, with no adjustments needed this morning. -Wilson

DISCUSSION

/Issued 411 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 / 0 0 0 10 HLN 38 22 38 28 / 0 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 / 10 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.