textproduct: Great Falls

KEY MESSAGES

- Locally windy conditions Monday may create some drifting and blowing snow. - Temperatures moderate back to near seasonal averages later this week.

- Periods of snowfall Monday night through Tuesday and again this upcoming weekend.

UPDATE

/Issued 830 PM MST Sun Nov 30 2025/ Updated forecast is out. Main adjustment this evening was to lower temperatures towards current trends in the cold spot. That being said, warmer air is slowly moving in from the west, as westerly winds increase. There is about a 40 degree change in temperature this evening from the Great Falls area being near 20 above to areas north of Havre that are near 20 below this evening. Thus the cold advisory will continue for Hill/Blaine counties. The warm air will continue to move in, but it will take time, and some areas will not mix out until Monday.

Otherwise, expect periods of snow to start tomorrow and then continue through the rest of the week. Tue/Wed looks to be the day when the snowfall is the most widespread. The current winter weather advisory for snow looks good, but additional areas might be added later this week. Brusda

DISCUSSION

/Issued 830 PM MST Sun Nov 30 2025/

- Meteorological Overview:

An amplified upper level pattern is in place with a deep upper low centered near Hudson Bay and ridging just off of the west coast and north to northwest flow aloft over the Northern Rockies. Meanwhile, the next shortwave disturbance upstream moves over the ridge through he Gulf of AK and drops south through the Pacific NW and Northern Rockies Monday night through Tuesday

A shallow cold airmass remains firmly in place across the plains still this afternoon, but will erode from the west and southwest tonight as surface high pressure over the Dakotas moves off to the east and lee-side troughing develops to the east of the Rockies. This sets up windy conditions across much of north-central MT by Monday afternoon as northwest flow aloft increases ahead of the next wave.

Snow develops along northern portions of the Continental divide (Glacier NP area) early Monday evening under warm advection ahead of the incoming wave. Areas of snow or snow showers become more widespread across the rest of the forecast area Wednesday as the wave moves across the area and lower level flow turns more northwesterly as surface high pressure rebuilds across AB.

Mainly dry weather with seasonably cool temperatures is expected Wednesday and Thursday before the next series of Pacific weather disturbances arrives beginning Friday. There is considerable spread in details involving the southward extent cold air centered north of the border and the timing/trajectory of these disturbances, but potential exists for several rounds of precipitation as these systems move through next weekend. Hoenisch

- Forecast Confidence & Scenarios:

While strong winds are not expected Monday, 35-40 mph wind gusts will be widespread across portions of north-central MT adjacent to the central MT mountains with higher gusts along the east slopes of the Rocky Mtn Front. A settled snow-pack will likely mitigate much of the blowing snow potential but snow drifting across roadways could still affect visibility in open exposed areas.

Winter weather advisories have been issued for the Monday night through Tuesday period for the Glacier NP/Rocky Mountain Front areas and central MT/Gallatin and Madison county mountain ranges. Marias Pass is likely to see a period of steadier snow with accumulation of 2-3 inches Monday night through Tuesday morning, while areas to the east see northwesterly upslope enhanced snow with a 30-50% probability for amounts in excess of 4 inches across the Little/Big Belt and Bridger ranges. Hoenisch

AVIATION

01/06Z TAF Period

Main concerns for Monday morning is fog developing in KHLN. Fog should prevail IFR/MVFR but there's a slight chance of visibilities dropping to IFR at times. West/southwest winds pick up later today across the North-Central MT plains. A wave of light snow arrives Monday evening. This can bring MVFR to IFR conditions. -Wilson

PRELIMINARY POINT TEMPS/POPS

GTF 8 34 28 35 / 0 0 40 80 CTB 5 31 23 33 / 0 0 30 60 HLN 9 34 25 35 / 0 10 40 80 BZN 2 31 21 35 / 0 0 40 70 WYS 0 25 14 28 / 0 10 60 90 DLN 11 36 23 37 / 0 0 20 40 HVR -19 31 20 35 / 0 0 50 60 LWT 3 35 23 33 / 0 0 30 70

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 5 PM Monday to 11 PM MST Tuesday for East Glacier Park Region-Southern Rocky Mountain Front.

Cold Weather Advisory until 10 AM MST Monday for Hill County- Northern Blaine County.

Winter Weather Advisory from 11 PM Monday to 5 AM MST Wednesday for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains-Snowy and Judith Mountains.