A cold front produced afternoon scattered showers and isolated thunderstorms across the region. A thunderstorm produced severe thunderstorm winds along the Hi-line.
Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS TFX wrote it up.
A cold front produced afternoon scattered showers and isolated thunderstorms across the region. A thunderstorm produced severe thunderstorm winds along the Hi-line. A strong pressure gradient setting up in Southwest Montana produced isolated strong wind gusts.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Great Falls, MT wrote its last area forecast discussion before the first event at May 12, 4:19 AM MST, 2 hours 41 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Great Falls MT 519 AM MDT Mon May 12 2025 Aviation Section Updated. .KEY MESSAGES... - Passing showers or isolated thunderstorms today. - Accumulating mountain snow, mostly above 7000 tonight for Southwest MT. - Additionally accumulating mountain snow Tuesday night over Southwest MT. - A slow cooling trend for afternoon temperatures this week. - The potential for a bit more widespread rainfall once again by late next weekend over Southwest MT. && .DISCUSSION... /Issued 356 AM MDT Mon May 12 2025/ - Meteorological Overview: Scattered showers/isolated thunderstorms continue to move from southwest to northeast through the CWA this morning. The main impact from any stronger storms will be gusty winds and small hail. By tonight, a stronger upper level trof will begin to approach Southwest MT. This will focus more of the heavier precipitation towards that portion of the state. Enough cold air will move in with the trof, that snow levels will fall to around 6500 feet or so. Overall snow is expected to accumulate in the higher elevations of Southwest MT tonight, thus a winter weather advisory was issued for that area. The precipitation does diminish a bit during the day on Tuesday, only to redevelop on Tuesday night, once again over the mountains of Southwest MT. Additional winter statements might be needed for the some mountain ranges of Southwest MT once again Tuesday night. From Wednesday through Saturday, a spring time weather pattern will reside over the CWA, resulting in passing showers/thunderstorms. The overall confidence in precipitation during this period is low, and most showers will be small/isolated, thus not producing a significant/widespread amount of precipitation. Next Sunday/Monday...the GFS model is more aggressive with a spring storm to affect portions of Southwest MT during this time. The EC model, also has some precipitation progged, but just not as much. Overall, there is still quite a bit of uncertainty on how strong the weather system for next weekend will be at this time. - Forecast Confidence & Scenarios: The main concern for weather will be in the mountains of Southwest MT tonight, in terms of how low the snow levels get, and how heavy the hourly snowfall rates will be. Overall, for mountain areas above 7000 feet, snow accumulations of several inches are expected. However, in the Pony area, some forecast models have progged heavier snowfall in that area, possibly in excess of 8 inches. Day shift will continue to monitor for a possible change to a winter storm warning for the Pony area should the higher snowfall amounts look to pan out. Brusda && .AVIATION... 12/12Z TAF Period Expect passing showers/isolated thunderstorms to continue to affect the CWA throughout the period. The showers will be brief this morning, as they are moving very quickly to the northeast. Do expect the precipitation to become a bit slower tonight, and a bit more widespread over Southwest MT. Snow levels will also lower to around around 7000 feet. Mountains/passes will be obscured at times across the CWA. Brusda Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 72 45 59 43 / 20 40 60 50 CTB 63 40 56 36 / 20 20 60 20 HLN 73 44 59 43 / 20 60 80 50 BZN 74 40 57 39 / 10 70 90 70 WYS 67 33 53 31 / 10 50 90 90 DLN 68 38 54 37 / 10 80 90 70 HVR 77 45 62 41 / 20 40 40 30 LWT 74 41 57 40 / 20 60 40 60 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 8 PM this evening to 9 AM MDT Tuesday for Elkhorn and Boulder Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Northwest Beaverhead County-Ruby Mountains and Southern Beaverhead Mountains. && http://www.weather.gov/greatfalls
Special Weather Statement
National Weather Service Great Falls MT
259 AM MDT Mon May 12 2025
MTZ301-302-120945-
East Glacier Park Region MT-Northern High Plains MT-
259 AM MDT Mon May 12 2025
...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN GLACIER COUNTY
THROUGH 345 AM MDT...
At 300 AM MDT, Doppler radar was tracking a strong thunderstorm 12
miles northwest of Kiowa, moving northeast at 50 mph.
HAZARD...Wind gusts of 50 to 55 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Many Glacier, Babb, Saint Mary, and Goat Haunt.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4900 11288 4899 11284 4875 11282 4855 11347
4872 11371 4878 11377 4882 11376 4884 11378
4884 11388 4895 11403 4899 11407
TIME...MOT...LOC 0859Z 233DEG 47KT 4867 11347
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...55 MPH
BrusdaSpecial Weather Statement
National Weather Service Great Falls MT
443 AM MDT Mon May 12 2025
MTZ301>303-121115-
East Glacier Park Region MT-
Eastern Glacier, Western Toole, and Central Pondera MT-
Northern High Plains MT-
443 AM MDT Mon May 12 2025
...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN
GLACIER COUNTY THROUGH 515 AM MDT...
At 442 AM MDT, Doppler radar was tracking a strong thunderstorm 20
miles northwest of Cut Bank, moving northeast at 50 mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This storm will remain over mainly rural areas of northeastern
Glacier County.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4899 11287 4900 11222 4853 11253 4870 11320
4900 11288
TIME...MOT...LOC 1042Z 215DEG 46KT 4876 11275
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
BrusdaThe Pocatello radar (KSFX), 236 km away, was scanning. The volume nearest the first event began at 21:46 UTC.
3 high wind, 1 thunderstorm wind. Local standard time, as filed.
Mesonet station MTM16 6.6 N Dell recorded a 59 mph wind gust.
Norris Hill MDT site measured high sustained wind 0f 43 mph over the span of an hour and a 58 mph wind gust.
Mesonet station HRKM8 Harkness RAWS measured a 58 mph and 60 mph wind gust.
Mesonet station EW1931 Rudyard measured a 63 mph thunderstorm wind gust.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2025Every state in 2025This day in weather historyWarnings in Montana, May 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1257703, 1257711, 1257706, 1257714.