textproduct: Great Falls

KEY MESSAGES

- Occasional light freezing rain and drizzle will impact the Bozeman, Dillon, and Helena areas through the mid to late morning hours today.

- Periods of mountain snow and some scattered areas of lower elevation light rain, snow, or mixed precipitation continue for much of the week.

- Near to above average temperatures are expected for most locations, but Arctic air will periodically move into central and north- central Montana.

UPDATE

Morning update has been published, with the main change being to cancel the Winter Weather Advisory for Eastern Toole and Liberty Counties, Hill County, Northern Blaine County, and Western and Central Chouteau County early as the threat for freezing rain/drizzle has largely diminished across these areas. With that being said an isolated shower producing freezing rain can't be ruled out, but showers have been struggling to spread east and north of a Cut Bank, to Great Falls, to Lewistown line. Otherwise the remainder of the forecast remains on track, with the remaining Winter Weather Advisories continuing through 11 AM MST. - Moldan

DISCUSSION

/Issued 450 AM MST Mon Dec 22 2025/

- Meteorological Overview:

Another wave of mountian snow and scattered areas of lower elevation rain/snow will continue to move through the forecast area through mid- to late morning. The primary concerns continue to be light snow impacts at the passes, along with some light freezing rain/drizzle over the colder valleys of southwest and central/north-central MT thanks to H700 temperatures warming to the -2 to -6C range and below freezing ground surfaces.

Precipitation diminishes and ends this afternoon with the passage of the responsible shortwave trough. Arctic air will move back southward and brush north-central Montana this evening and tonight, mostly impacting areas along the Hi-Line. A deepening trough along the Pacific NW coast will send another elevated warm front through the forecast area on Tuesday, resulting in more mountain snow and some lower elevation precipitation. Recent model guidance has been running a little less bullish with precipitation east of the Continental Divide for the Tuesday through early Wednesday period, but at least some scattered areas of light precipitation can be expected. The warming aloft will also bring another opportunity for spotty, light freezing rain/drizzle over the colder valleys.

The better chance of precipitation will come Wednesday into Thursday when a shortwave ejects northeastward into the Northern Rockies. The most notable change with this system from 24 hours ago is the warmer temperatures aloft. While there is still an expectation for surface level Arctic air to dive back southward into central/north-central MT, the shallow cold profile no longer looks to be supportive of widespread lower elevation snowfall, but rather lighter snow and mixed precipitation, including light freezing rain and drizzle. Mountain areas still look good for light accumulating snow during this time.

The aforementioned trough churning along the Pacific NW coast looks to finally head eastward into Montana Friday into Saturday for another round of snow and a southward intrusion of Arctic air. The cold air depth with this system should be sufficient for snow at all elevations, but still most widespread in the mountains. Ridging aloft then settles in for milder conditions later in the weekend into early next week before troughing and colder air returns heading into the new year. - RCG

- Forecast Confidence & Scenarios:

Snow and spotty light freezing rain/drizzle through the morning hours...

Waves of precipitation continue to stream in from the southwest while colder valley locations along the Continental Divide and over southwest MT remain below freezing. Winter weather advisories were sent out to include the Bozeman and Dillon areas for ongoing light freezing rain. Helena and Lincoln were also added in anticipation for the development of light freezing rain later this morning. Areas along the Hi-Line have remained dry thus far but no changes were made to the inherited advisory. While hires guidance has backed precipitation off some, at least spotty freezing drizzle can't be ruled out. Farther north, the immediate eastern slopes of the Rocky Mountain Front were added to the advisory due to ongoing light snow. Impacts for this morning will be greatest for the areas observing freezing rain and may include slippery roads/sidewalks causing hazardous conditions for travelers/pedestrians, isolated power outages, and aviation impacts.

More light freezing rain or drizzle possible Tuesday through Thursday...

At this time, precipitation on Tuesday into early Wednesday looks minimal for most locations east of the Continental Divide. The main concerns come with the arrival of a shortwave trough and the southward advancement of an Arctic boundary. If this trough does indeed lack colder air aloft, then central and north-central Montana will be looking at scattered areas of light freezing rain/drizzle late Wednesday through early Thursday morning while temperatures fall in teens and 20s. NBM probabilities weakly highlight this potential with around a 10 to 20% chance for a hundredth or greater of ice accumulation. This situation will be closely monitored as time progresses. - RCG

AVIATION

22/12Z TAF Period

A passing shortwave will maintain areas of light snow, rain, and freezing rain through 22/18Z, mostly concentrated along the Continental Divide and over Southwest MT. KBZN and KHLN will be most susceptible to light freezing rain/drizzle and MVFR/IFR conditions. Precipitation diminishes and ends this afternoon with partial clearing taking place and VFR conditions returning. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 46 27 45 27 / 30 0 0 0 CTB 38 15 39 19 / 20 0 0 10 HLN 43 28 46 31 / 80 10 20 0 BZN 46 30 50 32 / 60 20 10 0 WYS 41 30 42 27 / 90 90 40 0 DLN 46 30 47 32 / 60 20 10 0 HVR 35 11 33 20 / 40 0 0 10 LWT 46 27 48 33 / 40 10 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 11 AM MST this morning for Beaverhead and Western Madison below 6000ft-Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-East Glacier Park Region- Elkhorn and Boulder Mountains-Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains-Helena Valley- Northwest Beaverhead County-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.