textproduct: Great Falls

KEY MESSAGES

- A Pacific cold front moving across the region late today into early Thursday brings a round of mountain snow and a mix of lower elevation rain and snow through Thursday.

- Cooler temperatures linger into Friday before the region warms again this weekend, coinciding with the arrival of a period of breezy to at times strong winds.

- Another cold front looks to cool temperatures again heading into early next week, with larger uncertainty with respect to precipitation and the potential for additional gusty winds.

DISCUSSION

/Issued 1202 AM MST Wed Mar 4 2026/

- Meteorological Overview:

Zonal flow aloft early this morning will become increasingly southwesterly through the day ahead of an approaching trough from the Pacific NW. Initial impacts are largely confined to light precipitation along the Continental Divide through the day today. As the trough progresses inland the majority of the forcing within the trough splits southward. That said, there does appear to be a trend toward a slight bit more consolidation to this troughing, with a majority of guidance bringing a 700mb trough across Southwest Montana this afternoon into tonight. A Pacific cold front will push across the region late today and tonight associated with the broader scale troughing, shifting winds to be a more westerly to northwesterly direction at the surface and introducing cooler air to the region.

Precipitation looks to accompany this troughing and frontal passage, in the form of mountain snow and initially lower elevations rain. As cooler air works in behind the front, particularly across Southwest Montana, snow levels look to fall to valley floors later tonight. Adding to the complexity, high resolution ensembles do feature a small amount of instability ahead of the Pacific cold front across Southwest Montana, mainly east of I-15 and South of I- 90 this evening. Forcing from the larger scale troughing and approaching 700 mb trough look to be enough to result in at least a few showers in this area. Should these showers occur over higher terrain, brief and intense bursts of snow would be a reasonable expectation. While these showers do not look to be overly widespread, where they do occur there would be localized impacts. Given these showers look to be pre-frontal in nature, confidence in any snow at lower elevations associated with the convective activity is low at this time.

A northwesterly mid level flow behind the aforementioned 700mb trough looks to keep mainly mountain snow around into the day Thursday, particularly in areas that favor northwesterly upslope flow. Additionally, cool air aloft and a sufficient sun angle looks to result in some convective showers (Mix of rain, snow and graupel dependent on temperatures) across portions of the plains Thursday afternoon where enough insolation sneaks through cloud cover. The northwesterly flow aloft more or less persists into Friday (perhaps trending to northerly by the end of the day), keeping the region on the cooler side for another day, with lingering light mountain snow at times.

Looking toward the weekend, upper level ridging well off the Pacific coastline slumps eastward, resulting an a somewhat zonal at at times northwesterly flow aloft into early next week. Breezy winds look to develop in all areas this weekend, with strong winds at times in the typically windier areas over the plains as this stronger mid-level flow combines with an increasing pressure gradient at the surface and favorable ridgetop stability. Temperatures also respond to the increase in wind, trending back above average for both Saturday and Sunday across the region.

Looking toward Monday and Tuesday, an initially low amplitude shortwave slowly amplifies as it moves from the BC coastline toward the Northern Rockies. While there are some timing and strength uncertainties with this system, it does look to result in either a Canadian or Pacific cold front and period of precipitation. What we do know: The main takeaway for early next week will periods of precipitation, and temperatures trending back closer to normal. What we do not know at this time: Specifics such as any precipitation amount, snow levels, or timing of any more impactful period of winds (Should they occur) or precipitation. -AM

- Forecast Confidence & Scenarios:

Tonight into Thursday:

Confidence in the mid level troughing and associated precipitation moving across Southwest Montana and portions of Central Montana is high, evident by the European Extreme Forecast Index and Shift of Tails fixating on this area with EFI values exceeding 0.7 and SoT of 0 or higher for both QPF and snow. Given this is the case, and that ensemble average precipitation over these areas Wednesday night into Thursday is largely around or in excess of 0.5", I have opted for an initial round of Winter Weather Advisories for mountain areas where impacts look most likely by this evening. Should confidence increase in slightly higher amounts impacting roadways in the mountains south of Bozeman, an upgrade to a Winter Storm Warning would be warranted. Additional Winter Weather Advisories may also become necessary for the overnight into early Thursday, particularly near Homestake Pass and in the southeastern portion of the Gallatin Valley, including Bozeman. Further north in the Little Belts the better snow rates look to hold off til during the day Thursday, so I have opted to hold off on an advisory for this area for the time being.

Winds This Weekend:

Much of the weekend is looking at least breezy, thanks to a building pressure gradient. There are still some discrepancies as to when the most favorable timing will be for strong winds. The combination of the persistent pressure gradient and ridgetop stability (Supporting mountain wave activity) will certainly support strong winds developing at the surface over much of the plains whenever the most favorable winds aloft do end up arriving. To put some probabilities out there: The 10th percentile max wind gust for Saturday (90% probability to see a stronger gust) in Browning and Cut Bank are 70 mph and 58 mph respectively. These low end wind gust scenarios are largely similar, although ever so slightly lower, for Sunday. This points to high confidence in a period of strong winds at some point this weekend. High end scenarios for gusts in these two areas (10% probability to see a stronger gust) are 90 mph (Browning) and 80 mph (Cut Bank) on both Saturday and Sunday.

Sunday night through Tuesday:

The more progressive/lower amplitude scenario favors the Canadian cold front and lower winds for early next week over the plains, while the higher amplitude solutions are a bit further south and feature more of a Pacific front. The solution that favors the Pacific front would keep the gusty winds around through Monday across all areas. At this point there is roughly an equal probability for these two scenarios. -AM

AVIATION

04/12Z TAF Period

Westerly flow aloft across the Northern Rockies continues to gradually moisten from top down for increasing/thickening mid to high level clouds. An approaching Pacific frontal system has brought lower clouds, mountain obscuration, and some precipitation to areas along the Continental Divide. Lowering cloud- bases, areas of precipitation, and associated MVFR/IFR conditions will generally expand from west to east through central and southwest MT between 05/00 and 05/12Z. - RCG

FIRE WEATHER

Given the period of gusty winds that are favored this weekend, grassland areas that end up seeing little to no precipitation through the remainder of the week will be a concern for fire weather conditions. Relative humidity does not look quite as low, but should the strongest winds coincide with peak daytime heating, elevated fire weather conditions would be a reasonable expectation. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 57 35 46 28 / 10 70 60 40 CTB 52 28 47 24 / 20 20 30 30 HLN 55 33 45 27 / 30 80 70 40 BZN 56 29 44 24 / 0 80 80 50 WYS 43 24 36 14 / 10 90 90 50 DLN 52 29 42 23 / 10 90 60 10 HVR 58 27 46 23 / 10 50 40 30 LWT 57 32 42 25 / 0 40 70 50

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 8 PM this evening to 3 PM MST Thursday for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains.

Winter Weather Advisory from 3 PM this afternoon to 9 AM MST Thursday for Northwest Beaverhead County.