textproduct: Great Falls

KEY MESSAGES

- Light snow this morning, diminishes in many areas for a few hours, before another round of snow moves in this evening.

- Some rain could mix in at times at lower elevations over the next few days.

- Several periods of strong winds are possible over the next few days as well, some of which could require high wind statements.

UPDATE

/Issued 758 AM MST Fri Dec 5 2025/

Snow will continue in the mountains of Central and Southwestern Montana today with a band of snow impacting a portion of North- central Montana this afternoon through tonight. There will also be light snow in some of the valleys of Southwestern Montana this afternoon through tonight. For the update, PoPs were adjusted this afternoon/evening to account for the frontal timing in the latest hi-res model guidance. Since snow has ended in the Gallatin Valley and in the Boulder and Elkhorn Mountains those Winter Weather Advisories were cancelled. The rest of the forecast is on track. -IG

DISCUSSION

/Issued 408 AM MST Fri Dec 5 2025/

- Meteorological Overview: The overall pattern change from a drier November, to a wetter more typical La Nina weather pattern is beginning. Expect weather systems to move mainly from west to east across Montana on regular intervals, generally every 1 to 3 days over the next few weeks. Each weather system might not be as strong as the previous weather system, but do expect periods of precipitation, along with short periods of mild temperatures, followed by short periods of cold temperatures. That being said, the first wave of moisture is starting to exit the CWA this morning. Light snow is diminishing over Southwest MT. The current advisories set to expire at 11 AM in the Boulder and Bozeman area might be cancelled a bit early, as the snow is diminishing. Otherwise, a break in the precip is expected for a few hours this morning into early this afternoon.

By this evening, the next, and a bit stronger wave of precipitation will move from west to east across the CWA. This wave tonight will pack more of a punch, and also impact a larger portion of the CWA. This wave of moisture should arrive along the divide by 4 PM, and then move rather quickly across the CWA this evening and overnight. There is the potential that a snow squall warning might be needed for a few areas along the I-15 corridor from Helena to Great Falls early this evening if the system is early. Otherwise, the band of heavier snow is likely to occur after 7 PM, likely getting a bit late for snow squall warnings. Since this band is quick in the Great Falls/Helena area, and it could mix in with rain, no advisory at this time for this area. For areas north/east of Great Falls, it will be later, and mostly snow, thus an advisory was issued. Overall for the mountains, a 6 to 12 inch snowfall is possible tonight, thus the current warnings will remain. For the winter storm watch along the divide, the highest snow amounts are right near the divide, thus day shift will consider if an advisory might be better for that area. Otherwise, the main concern this evening will also be for blowing snow. A few ridge top could have wind gusts near 60 mph as the front moves through. Overall, most of the snow moves out by Saturday afternoon.

For Sunday through Friday, the progressive westerly flow pattern will continue. Just scattered mountain showers are mainly expected Sun/Mon...but by Tue the precip becomes more widespread once again. From Tue thru next Friday, there is the potential for daily snowfall amounts of 2 to 4 inches in the mountains, with isolated higher amounts. At lower elevations, rain will mix in at times during the week, so snow amounts are very minor, with most areas seeing less than a quarter of an inch, if that, on a daily basis. Lower elevation temperatures will generally be above normal for all of next week. There will also be the potential for several periods of strong winds. Again, almost daily Sun through Thu there is the potential for some areas to be near high wind warning criteria.

- Forecast Confidence & Scenarios: The main concern in the short term is the band of snow that will move across the CWA this evening. The western portions of the CWA will be affected during the evening hours, while blowing snow increases, and poor visibility will affect the eastern portions of the CWA. There is the potential that snow squalls might be needed if temperatures cool quicker this afternoon and the snow arrives a bit early.

Otherwise, the potential for strong winds will be a concern over the next few days. Right now Tuesday is showing the highest probability of strong winds, with near an 80 percent chance for areas along the Rocky Mountain Front and around Cut Bank. Thus high wind statements might be needed at times over the next few days. Brusda

AVIATION

05/18Z TAF Period

A moist and unsettled northwesterly flow aloft will remain over the Northern Rockies for at least the next 24 to 48 hours. MVFR/IFR clouds and mountain obscuration will mostly be confined to areas near mountains through 06/00Z. Then a fast moving shortwave will bring increased snow shower activity and some MVFR/IFR conditions to all areas between 06/00 and 06/09Z. Steadier snow and degraded flight categories will linger into Saturday in the mountains and near the KHVR/KLWT areas. Mountain top winds will exceed 50 kts at times during the passage of the shortwave which will increase mountain wave turbulence and instances of low level wind shear. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 39 22 33 23 / 20 80 50 10 CTB 29 11 25 13 / 20 70 20 10 HLN 40 30 40 28 / 40 90 60 20 BZN 36 26 40 22 / 60 90 60 20 WYS 30 19 33 14 / 90 90 80 40 DLN 38 28 40 21 / 40 80 20 10 HVR 37 10 19 6 / 40 90 60 50 LWT 35 20 33 20 / 40 90 70 40

TFX WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from 5 PM MST this afternoon through Sunday morning for East Glacier Park Region-Southern Rocky Mountain Front.

Winter Weather Advisory from 8 PM this evening to 5 AM MST Saturday for Bears Paw Mountains and Southern Blaine-Eastern Toole and Liberty-Fergus County below 4500ft-Hill County- Northern Blaine County-Snowy and Judith Mountains-Western and Central Chouteau County.

Winter Storm Warning until 2 PM MST Saturday for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains.

Winter Storm Warning until 5 PM MST Saturday for Northwest Beaverhead County.