Respectably strong southerly flow aloft on the western edge of a ridge combined with a modest pressure gradient to result in strong sustained winds in the Madison River Valley.
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The episode as NWS TFX wrote it up.
Respectably strong southerly flow aloft on the western edge of a ridge combined with a modest pressure gradient to result in strong sustained winds in the Madison River Valley.
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 Apr 15, 2:49 PM MST, 1 hour 1 minute earlier. Its key messages:
Area Forecast Discussion National Weather Service Great Falls MT 349 PM MDT Wed Apr 15 2026 .KEY MESSAGES... - Chances for lower elevation rain/isolated thunder and mountain snow increases this afternoon and evening. - A cold front will transition rain to snow, bringing cold temperatures Thursday and a slight chance for snow squalls along I-90 tonight. - Isolated to scattered snow showers continue Thursday afternoon into Friday morning. - A warming trend and drier conditions trending for the weekend and into the beginning of next week. && .DISCUSSION... - Meteorological Overview: With the upper level trough translating east across the Western U.S., isolated lower elevation rain and mountain snow showers have developed. Precipitation will continue to develop, becoming scattered ahead of the front. Weak instability this afternoon poses an isolated risk for weak thunderstorms. Gusty winds across the Madison River and Beaverhead County valleys also increases ahead of the front as winds increases aloft. The cold front passage later today will bring widespread precipitation across the region. Strong cold air advection behind the front combined with weak instability brings a slight risk for snow squalls along and south of the I-90 corridor this evening. The main impacts will be sudden reductions in visibility and minor, slushy accumulations on roads. Snow levels dropping behind the front will help transition rain to snow widespread across the region late tonight and into Thursday morning. Chilly temperatures during the day Thursday will keep lingering snow showers throughout the day, mainly in Southwest MT with more isolated snow showers across North-Central MT. Increasing winds aloft wrapping around the cold upper-level low along the Hi-line Thursday will also bring breezy to gusty winds to North-Central MT. -Wilson On Friday, North-central, Central, and Southwestern Montana remain under the influence of the upper-level trough. This will cause temperatures to remain on the chillier side with lows in the teens and another round of snow showers Friday morning. As the trough moves to the east, an upper level ridge of high pressure to the west begins to build, allowing temperatures to warm in the afternoon and precipitation chances to decrease. The upper level ridge will move east over Montana on Saturday and Sunday and bring milder and drier weather across the region. Early next week the benign conditions continue until troughing brings increased shower activity by the middle of next week. - Dzomba - Forecast Confidence & Scenarios: Winds in Southwest MT Through the Rest of the Day: Gusty winds continue this afternoon in the Madison and Beaverhead County Valleys. The threat for high winds remain marginal, with best chances being with a shower/thunderstorm or along the frontal passage. Therefore, no changes were made to the current High Wind Warning. Snow Through Thursday: Warmer pavement temperatures are currently limiting snow accumulations to above pass level. The cold front will help lower temperatures, with moderate to heavy snow along the front helping crash pavement temperatures to freezing. The main changes to the forecast was upgrading the Madison and Gallatin County Mountains to a Winter Storm Warning and downgrading the Winter Storm Watch to a Winter Weather Advisory for the Gallatin County Valley. One uncertainty lies in the amount of QPF this system produces, as probabilities have down trended recently in model runs. Though synoptic nudges like the strong cold advection and aloft and frontogenesis along the front gave enough confidence to upgrade the Madison and Gallatin County Mountains to a Winter Storm Warning. The main impacts will be along Highway 191 south of the Gallatin Gateway to West Yellowstone. Timing of the front being at night is ideal for moderate to heavy snow along the frontal passage to crash road temperatures in the Gallatin Valley quickly. However, there wasn't a high enough confidence in high moisture amounts to produce a broader 6-7" of snow for a Winter Storm Warning. There is a slight chance for those amounts still, especially areas near the higher terrain that could get some upslope enhancement. A tight snow gradient will likely develop in the valley/the city of Bozeman as a result. The Madison River Valley could see minor slushy snow accumulations Thursday, so they were added to the Winter Weather Advisories as well. -Wilson && .AVIATION... 15/18Z TAF Period A cold front is moving through North-central, Central, and Southwestern Montana this afternoon and evening. This will change the wind direction at all terminals to more northerly and bring rain and snow to all TAF sites during this TAF Period. At the KBZN and KEKS terminals between 15/21Z and 16/06Z there is a a 15 - 20% chance for lightning. At the KWYS terminal between 16/03Z and 16/08Z there is a 15 - 20% chance for lightning. At the KHLN, KGTF, and KLWT terminals between 15/21Z and 16/03Z there is a 10 - 20% chance for lightning. During the duration of this TAF period at most of the terminals there is 30% chance or greater for rain, a rain/snow mix, or snow showers. During the majority of this TAF period there will be mountain obscuration across North-central, Central, and Southwestern Montana. Between 15/22Z and 16/06Z there will be isolated instances of mountain wave turbulence and low- level wind shear across Southwestern Montana. Across southwestern Montana this afternoon there is a low chance that a rain shower could mix down strong wind gusts in excess of 40kts. -IG && .PRELIMINARY POINT TEMPS/POPS... GTF 27 39 22 45 / 80 50 30 50 CTB 19 32 16 44 / 40 40 20 20 HLN 27 42 25 45 / 90 60 30 70 BZN 25 40 19 43 / 100 80 40 70 WYS 24 33 12 36 / 100 100 70 70 DLN 25 38 19 42 / 90 80 20 30 HVR 25 36 17 44 / 90 30 20 10 LWT 26 38 18 41 / 90 50 20 40 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MDT Thursday for East Glacier Park Region. Winter Weather Advisory from 6 PM this evening to noon MDT Thursday for Big Belt, Bridger and Castle Mountains-Little Belt and Highwood Mountains-Southern Rocky Mountain Front. Winter Storm Warning from 6 PM this evening to midnight MDT Thursday night for Gallatin and Madison County Mountains and Centennial Mountains. High Wind Warning until 9 PM MDT this evening for Beaverhead and Western Madison below 6000ft-Madison River Valley. Winter Weather Advisory from midnight tonight to 6 PM MDT Thursday for Gallatin Valley-Madison River Valley. Winter Weather Advisory from 6 PM this evening to 6 AM MDT Thursday for Northwest Beaverhead County. && http://www.weather.gov/greatfalls
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Both AWOS station KEKS Ennis Airport and mesonet MTNOR Norris Hill measured sustained winds averaging 40 mph over an hour.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2026Every state in 2026This day in weather historyWarnings in Montana, April 2026
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: 1330140.