textproduct: Great Falls

KEY MESSAGES

- On Saturday it will be cool and mostly dry.

- On Sunday there will be snow along the Rocky Mountain Front with windy conditions in the valleys of Southwestern Montana.

- On Sunday there will be snow along the Rocky Mountain Front with windy conditions in the valleys of Southwestern Montana.

DISCUSSION

/Issued 150 PM MDT Fri Sep 11 2026/

- Meteorological Overview:

An upper-level trough associated with a surface cold front is exiting North-central, Central, and Southwestern Montana this afternoon. This will bring cool (below seasonal average) temperatures to the area with lingering rain showers. On Saturday an upper-level ridge builds in briefly over North-central, Central, and Southwestern Montana. This will bring mostly dry weather with status quo temperatures to the area. On Saturday along the Rocky Mountain Front there will be snow mixed with rain at times and primarily all rain at lower elevations. On Sunday a closed upper- level low will move over North-central, Central, and Southwestern Montana with a 700mb low moving over southern Alberta/the Hi-Line. This will bring strong southerly flow aloft which will bring strong winds to north-south orientated valleys of Southwestern Montana. On Sunday along the higher peaks of the Rocky Mountain Front there will be snow with the rest of the Rocky Mountain Front seeing rain and/or a rain/snow mix. On Sunday across the rest of North-central Montana there will be light rain showers. On Sunday warm air advection will bring seasonable temperatures to Southwestern Montana with below seasonal average temperatures north of the I-90 corridor.

On Monday the upper-level low exits North-central, Central, and Southwestern Montana. Precipitation will linger across North-central Montana on Monday. On Monday low-level winds will increase which will bring at least breezy conditions to North-central Montana. On Monday temperatures will remain cool. Tuesday through Thursday an upper-level ridge gradually builds in over North-central, Central, and Southwestern Montana. This will allow temperatures to warm back up to near seasonal averages with mostly dry weather. -IG

- Forecast Confidence & Scenarios:

On Sunday there is a 40 - 80% chance for sustained winds of 40 mph and a 50% chance for wind gusts of 55 mph or greater in the Madison River Valley. As a result a High Wind Watch was issued for the Madison River Valley from 12 PM to 9 PM on Sunday. On Sunday there is greater than a 50% chance for 55 mph wind gusts along the ridgetops of the Madison and Gallatin Mountains. On Monday there is a 30 - 50% chance for wind gusts of 55 mph or greater across most of North-central Montana.

On Sunday there are differences in the 700 mb low track between the GFS and Euro. The Euro the low tracking slightly further south which would bring more precipitation/snow to the Northern Rocky Mountain Front than what the GFS has. There is a 50 - 80% chance for one inch of snow or greater along the majority of the Rocky Mountain Front Sunday into Monday. There is a low chance that isolated mountain peaks will receive in excess of 6 inches of snowfall Sunday into Monday. On Tuesday morning there is a 40 - 60% chance for low temperatures of 36 degrees or colder across the Hi-Line and the valleys of Southwestern Montana. -IG

AVIATION

12/00Z TAF Period

Isolated showers will continue to move out of the area leaving low cloud decks, particularly across Central and North Central Montana. Low-VFR conditions are expected throughout the TAF period in southwest Montana as precipitation will remain to the north, though mountain obscuration is possible with peaks above 6kft. Across north-central Montana, low-VFR to MVFR conditions are expected through the end of the TAF period with continued low cloud bases and isolated rainshowers which may briefly drop visibility to 4-5 SM. Temporary IFR conditions are possible at terminal KCTB where cloud bases may approach 1kft between 12/12z and 12/16z. Winds will remain consistent and light across all terminals with the exception of KEKS where sporadic gusts of 15-20kt remain possible till 12/08z. -JR

PRELIMINARY POINT TEMPS/POPS

GTF 56 44 57 41 / 90 10 20 0 CTB 53 40 51 37 / 80 30 20 0 HLN 63 43 64 43 / 90 0 10 10 BZN 70 44 70 42 / 20 10 0 0 WYS 68 32 72 38 / 10 10 0 0 DLN 73 39 74 41 / 0 0 0 0 HVR 63 39 59 37 / 60 10 20 0 LWT 56 40 58 39 / 90 20 20 10

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Watch from Sunday afternoon through Sunday evening for Madison River Valley.