textproduct: Great Falls

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

/Issued 349 PM MDT Wed Apr 15 2026/

- 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

16/00Z TAF Period

A Pacific trough and attendant cold front will move through the forecast area in a northwest to southeast fashion through around 16/06Z, bringing areas of rain/snow showers, variable winds, and eventually a northerly wind shift. MVFR/IFR/LIFR conditions will become more expansive tonight into Thursday due to areas of snow and lowering stratus. The worst conditions will be for areas near the north/northwesterly aspects of terrain. Cold north/northwesterly flow aloft will then maintain scattered to numerous snow shower activity and intermittent degraded flight categories for remainder of Thursday and even into Friday. - RCG

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 until noon MDT Thursday for Big Belt, Bridger and Castle Mountains-Little Belt and Highwood Mountains- Southern Rocky Mountain Front.

Winter Storm Warning until 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 until 6 AM MDT Thursday for Northwest Beaverhead County.