textproduct: Great Falls

KEY MESSAGES

- Strong, gusty winds peak over central and north-central Montana and along the Rocky Mountain Front early this afternoon and then over the southwest later in afternoon and evening.

- Mountain snow will continue through this evening, mostly along the Continental Divide and over southwest Montana. There will also be scattered rain and snow showers or squalls over lower elevations during the cold frontal passage.

- Another round of mountain snow arrives late Sunday into Monday.

- Near to above average temperatures are generally expected, but Arctic air will brush northern areas later today through Saturday and again on Monday.

DISCUSSION

/Issued 345 AM MST Fri Dec 19 2025/

- Meteorological Overview:

A broad Pacific trough and attendant cold front will maintain another day of strong, gusty winds and mountain snow through this evening. The focus of the strongest winds will shift southward as the day progresses and the increasingly latitudinal oriented cold front sags southward.

While snow impacts will primarily be over the mountains lower elevations may also see some brief locally heavy rain, and snow showers in the afternoon and evening, particularly over central and southwest MT. A lobe of Arctic air will also clip northern areas later this afternoon through Saturday with the longest residence time along the Hi-Line.

Flat ridging aloft moves over the Northern Rockies Saturday into Sunday for drier conditions and lighter winds. Moisture streaming in from west of the Continental Divide will be sufficient for continued light snow along the immediate eastern slopes of the Rocky Mountain Front.

The next Pacific trough moves in later Sunday into Monday and brings another round of mountain snow, along with another shot of Arctic air over the plains. Mountain snow looks to be on the lighter side with this more subtle wave and strong winds are generally not expected.

Southwesterly flow aloft develops Tuesday through Thursday and brings lighter end mountain snow and near to slightly above temperatures. The next notable trough looks to arrive heading towards the middle and end of the work week. More mountain snow and some Arctic air over the plains can be expected with this system. - RCG

- Forecast Confidence & Scenarios:

Periods of strong winds through this evening...

Current mesoscale analysis shows a wide swath of 60 to 80 kt H700 westerly flow over the forecast area this morning. Surface transfer has steadily increased and scattered areas of wind gusts over 60 mph are being observed over central/north-central and southwest MT. Upper level winds drop off some later this morning, but diurnal mixing and a cold frontal passage should maintain periods of strong winds through this evening with the focus of the strongest winds slowly shifting southward as the day progresses. Given the current trend and NBM probabilities for wind gusts exceeding 55 mph running above 70% for much of the area, the high wind warnings were expanded to include nearly all of the forecast area with the exception of northern Hill/Blaine and the western Beaverhead zones. The Bozeman, Dillon, and Helena areas were placed in the warning, but it's important to note that the occurrence of wind gusts over 60 mph will be far more isolated than the previous event.

Mountain snow and scattered lower elevation rain/snow showers/squalls...

Mountain snow will continue through this evening along the Rocky Mountain Front and over the southwest mountains south of I90. The inherited winter weather advisories still look good for an additional 2 to 6 inches of snow through this evening. There will also be a line of rain and snow showers/squalls that will mostly impact southwest and central areas along and south of a Lincoln to Lewistown line. Mountain passes will generally see the most impacts from this activity including brief periods with reduced visibility below a half mile and slippery roads. Confidence is lower for lower elevations such as Helena and Bozeman, mostly because the colder air aloft may not be in phase with the core of heaviest precipitation, resulting in rain at the onset. - RCG

AVIATION

19/12Z TAF Period

An approaching Pacific trough will maintain periods of gusty to at times strong winds, mountain wave activity, and instances of low level wind shear through 20/03Z. Scattered rain/ snow showers and brief MVFR conditions associated with a Pacific front will mostly impact central and southwestern areas along and south of a Lincoln to Helena line between 19/15 and 20/00Z. Farther north, a Canadian front crosses the international border around 19/18Z and brings a northerly wind shift to the Hi-Line terminals. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 50 26 40 27 / 20 0 0 0 CTB 40 16 35 24 / 10 0 0 0 HLN 47 23 38 20 / 90 0 0 0 BZN 50 18 37 18 / 80 40 0 0 WYS 37 7 26 15 / 100 80 10 20 DLN 49 18 33 17 / 90 30 0 0 HVR 42 3 27 16 / 10 0 0 0 LWT 47 21 35 23 / 40 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 PM MST this evening for East Glacier Park Region-Southern Rocky Mountain Front.

High Wind Warning until 6 PM MST this evening for Bears Paw Mountains and Southern Blaine-Cascade County below 5000ft-East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Fergus County below 4500ft-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Madison River Valley-Northern High Plains-Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front-Western and Central Chouteau County.

Winter Weather Advisory until midnight MST tonight for Gallatin and Madison County Mountains and Centennial Mountains.

High Wind Warning until 9 PM MST this evening for Beaverhead and Western Madison below 6000ft-Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-Elkhorn and Boulder Mountains- Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains-Gates of the Mountains-Helena Valley- Missouri Headwaters-Ruby Mountains and Southern Beaverhead Mountains-Upper Blackfoot and MacDonald Pass.

Winter Weather Advisory until 9 PM MST this evening for Northwest Beaverhead County.