textproduct: Great Falls

KEY MESSAGES

- Wintry mixed precipitation and freezing rain ends in a southwest to northeast fashion this morning.

- Temperatures will be mild for most for the next couple of days, although colder air will linger along the Hi-Line.

- Another weather system and attendant cold front will bring a period of areawide light snow and and much colder temperatures late Friday into Saturday.

- Temperature will trend near to above average for most locations heading into early next week, but the colder air will linger along the Hi-Line and over the southwest valleys.

UPDATE

/Issued 808 AM MST Thu Dec 25 2025/

8 AM Update: Lingering precipitation has moved off to the east, with just isolated pockets of precipitation remaining. Given this is the case, the Winter Weather Advisory was canceled early. Those traveling over the plains should still plan for slick roads, as temperatures still remain close to or below freezing this morning.

Warmer air at the surface will continue to develop through the day today over the plains, though areas northeast of a Cut Bank to Lewistown line are likely to remain cool today. Meanwhile across Southwest Montana, daytime temperatures will remain on the mild side once again.

Patchy fog remains in a few spots this morning, though is much less widespread than overnight. Hence, the Dense Fog Advisory has also been canceled early.

Southwesterly flow aloft will continue today ahead of troughing near the Pacific coastline. Additional waves ejecting from this trough will promote periods of mainly mountain precipitation over the next day or so. Cool enough air aloft will be in place that I cannot rule out a rumble of thunder each of the next two afternoons, mainly across Central and Southwest Montana where surface temperatures are warmest.

A final piece worth mentioning is that a belt of stronger mid level southwesterly flow moves across Central and Southwest Montana during the day Friday. Regardless of any shower or potential thunderstorm development, these areas look to be on the gusty side through much of the day. High Wind highlights are currently not anticipated, but trends will be monitored. -AM

5 AM Update: One more wave of freezing rain is currently moving eastward through the plains where severe driving conditions are still being observed from the previous round. The winter weather advisory was extending through 9 am for all areas except the E Glacier/W Toole zone. Temperatures will warm and precipitation will end from southwest to northeast through mid- morning. - RCG

DISCUSSION

/Issued 808 AM MST Thu Dec 25 2025/

- Meteorological Overview:

An additional round of mixed precipitation and freezing rain will continue to move east and northeast over the plains for next few hours with the Arctic air retreating north as the precipitation ends later this morning. Mild and breezy to windy conditions generally prevail for the next day or so with a weak shortwave bringing more mountain snow tonight into Friday.

The next system arrives late Friday into Saturday and will be stronger and colder than previous ones with H700/H500 temperatures falling to -15C/-30C near its axis. This will result in more substantial mountain snow and even lower elevation light snow during the frontal passage. This upper level support will send the Arctic boundary all the way into southwest MT, at least briefly.

A Northwesterly flow aloft will set up heading into early next week while high pressure builds to our west. Milder and breezy conditions look to return for most locations, but the colder air may be reluctant to leave the normally colder river/wind protected valleys of north-central and southwest MT. - RCG

- Forecast Confidence & Scenarios:

Freezing rain, drizzle, and patchy fog diminishes and improves from southwest to northeast this morning...

The main area of freezing rain has crossed the Canadian border leaving a widespread coating of ice generally ranging from trace amounts to around 0.05 inches. Despite the low precipitation amounts, the impacts to roads have been rather significant with severe driving conditions and scattered road incidences being reported between Dearborn and Havre and then in the Choteau area. Another wave of freezing rain will move through between now and mid-morning and bring an additional few hundredths of an inch of incing. The latest hires guidance shows the last of the freezing rain exiting the Hi-Line around 9 to 10 AM. The winter weather advisory was extended for this area while the remainder advisory area to the south and west tentatively looks ok to expire at 5 am with lighter precipitation and warmer air poised to move in from the southwest.

Mostly mountain snow and winds tonight through Saturday...

A weak shortwave will bring a round of mountain snow tonight into Friday, mostly impacting the Northern Rocky Mountain Front and the southern portion of the Madison and Gallatin mountain ranges. The latter will have the best chance (50 to 80%) for 3 inches of snow or more.

The stronger and colder trough will arrive late Friday into Saturday and will deliver a more widespread snowfall. Snow will again be heaviest in the mountains, especially along the Rocky Mountain Front where Marias Pass stands around a 50% chance for 6 inches of snow or more. With an Arctic airmass finally being able to clear the entire forecast area on Saturday, most lower elevation look to see amounts ranging from a trace up to a couple of inches. Winds don't look overly impressive with either of the aforementioned systems, but locations along the Rocky Mountain Front look to see wind gusts over 60 mph at times on Friday. - RCG

AVIATION

25/18Z TAF Period

Main concern right now is dense fog in the Havre area. Satellite shows it is a thin band of fog, so it should burn off mid afternoon. Otherwise, breezy winds expected over North Central MT. Expect increasing clouds tonight, with rain/snow showers developing mostly after 06z Fri. Showers become a bit convective on Friday afternoon, with an isolated thunderstorm possible over Southwest MT. Looking ahead, a strong cold front will move southward on Saturday morning, expect a wind shift along with some light snow. Mountains/passes will generally become obscured after 05z Friday. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 50 34 50 9 / 40 10 20 20 CTB 43 24 38 -2 / 30 10 20 30 HLN 49 31 46 22 / 20 20 30 50 BZN 51 32 49 23 / 30 20 40 30 WYS 40 28 36 18 / 70 70 90 70 DLN 49 31 44 24 / 20 20 40 20 HVR 30 23 38 3 / 70 10 20 20 LWT 51 35 50 13 / 20 10 10 20

TFX WATCHES/WARNINGS/ADVISORIES

None.