textproduct: Great Falls

KEY MESSAGES

- Gusty winds today will result in localized blowing and drifting snow. - Widespread snowfall expected tonight through Tuesday night, with generally light accumulations at lower elevations with more notable accumulations in the higher terrain. - Another widespread snowfall event is possible over the weekend.

DISCUSSION

/Issued 355 AM MST Mon Dec 1 2025/

- Meteorological Overview:

Transient upper level ridging will slide across the area today, which will result in some gusty winds across the plains today. These winds have already started to make their presence known overnight, and have been hard at work eroding the arctic air mass and as a result many areas were warmer at 3AM than they were at sunset last night. Things have been a bit different in the valleys of Southwestern Montana, however, where temperatures have remained colder due to the mountains keeping the cold air locked in place.

Snow will return to the area later today and tonight as a shortwave trough approaches from the northwest. While snowfall will be heaviest over the higher terrain, most areas should see at least some light snowfall between tonight and Tuesday as this system moves through. Colder air will return to the area behind this system, but temperatures will not be quite as cold as they were over the weekend.

Behind this system, more tranquil but slightly breezy conditions appear likely as northwesterly flow aloft sets up across the area. Unsettled weather looks to make a return Friday or Saturday, however, as yet another disturbance moves through the area.

- Forecast Confidence & Scenarios:

Blowing snow today: As upper level ridging builds into the area, winds across the plains will increase, which could result in some blowing and drifting of the snowpack across the area. However, with only a minimal snowpack across the area any blowing snow concerns will be short lived.

Late week snow: While the arrival of some snowfall Friday and Saturday is appearing more and more likely, there remains some uncertainty as to how much snow will fall and how widespread an area the snow will affect. Right now the most likely scenario appears to be a quick hitting snowfall that drops anywhere between 1-4 inches across the lower elevations, but I cant rule out a scenario where northerly winds behind this system bring some more snow to the northerly upslope areas. Ludwig

AVIATION

01/12Z TAF Period

Aside from some low stratus and thin fog at KHLN this morning, VFR conditions are expected across the area through this evening. However, expect cigs to begin to lower overnight tonight with some snow moving into the area overnight tonight, bringing reductions in vis and cigs. Ludwig

PRELIMINARY POINT TEMPS/POPS

GTF 36 28 34 17 / 10 40 90 60 CTB 32 23 33 8 / 0 30 70 30 HLN 36 25 35 18 / 10 40 80 50 BZN 35 21 35 15 / 0 50 80 50 WYS 25 15 28 6 / 10 70 90 40 DLN 37 23 37 15 / 0 30 40 20 HVR 30 20 35 5 / 10 40 60 30 LWT 35 23 33 13 / 0 30 80 60

TFX WATCHES/WARNINGS/ADVISORIES

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

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

Winter Weather Advisory from 11 PM this evening 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.

Winter Weather Advisory from 5 AM Tuesday to 5 AM MST Wednesday for Cascade County below 5000ft-Fergus County below 4500ft-Gates of the Mountains-Helena Valley-Judith Basin County and Judith Gap-Upper Blackfoot and MacDonald Pass.