textproduct: Great Falls

KEY MESSAGES

- This afternoon it will be cool with isolated showers along the Hi-Line.

- On Sunday there will be snow along the Rocky Mountain Front with isolated rain showers/thunderstorms across the rest of North-central Montana.

- On Sunday it will be windy across the north-south orientated valleys of Southwestern Montana.

- On Monday precipitation will linger with windy conditions across the plains of North-central Montana.

DISCUSSION

/Issued 230 PM MDT Sat Sep 12 2026/

- Meteorological Overview:

This afternoon 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. Along the Rocky Mountain Front this afternoon there will be snow mixed with rain at times and primarily all rain at lower elevations. This afternoon/evening there will be isolated rain showers along the Hi- Line. On Sunday a closed upper-level low will move over North- central, Central, and Southwestern Montana with a 700mb low moving over southern Alberta. 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 a frontal boundary will move from west to east and bring rain showers with embedded thunderstorms. Some of these rain showers/any thunderstorms have the potential to produce gusty winds. See the Forecast Confidence & Scenarios section for details. On Sunday warm air advection will bring seasonable temperatures to Southwestern Montana with near normal 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 zonal flow with shortwave troughs moving through will affect North-central, Central, and Southwestern Montana. This will allow temperatures to be slightly below seasonal averages with isolated showers around. On Friday an upper-level ridge moves over North- central, Central, and Southwestern Montana. This will bring above normal temperatures with dry weather to the area. -IG

- Forecast Confidence & Scenarios:

On Sunday there is a 40 - 60% chance for sustained winds of 40 mph or greater and a 20 to 50% chance for wind gusts of 55 mph or greater in the Madison River Valley. As a result a High Wind Watch remains in effect for the Madison River Valley from 12 PM to 9 PM. 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 around a 50% chance for wind gusts of 55 mph or greater across Judith Basin and Fergus Counties. Due to a lack of 700 mb support for strong winds for Judith Basin County, a High Wind Watch was only issued for Fergus County from 9 AM to 6 PM on Monday.

There is a 50 - 80% chance for a tenth of an inch of snow or greater along the majority of the Rocky Mountain Front Sunday into Monday. There is currently a low chance that isolated mountain peaks will receive in excess of 3 inches of snowfall. Sunday into Monday there is a 30 - 60% chance for a quarter inch of precipitation or greater across North-central Montana. Sunday evening a line of showers will move through North-central Montana. As this line moves east of US Highway 87 between Great Falls and Havre there is a low chance for an embedded thunderstorm to produce gusty to strong winds. If temperatures continue to trend upward on Sunday that will increase the instability and lead to a greater risk for a thunderstorm to produce gusty to strong winds. On Tuesday morning there is a 30 - 60% chance for low temperatures of 36 degrees or colder across the valleys of Southwestern Montana. -IG

AVIATION

13/00Z TAF Period.

The primary concern tonight through Sunday morning will be low stratus and even some patchy fog along the Rocky Mountain Front and over/near the central island ranges. Other than KCTB being impacted with a period of degraded cigs Sunday morning, mountain obscuration over the aforementioned areas will be the primary impact. Then a mid level closed low pressure system approaches the Northern Rockies on Sunday and brings gusty south/southwesterly winds to southwest MT. Farther north, easterly winds will gust over 25 kts at times at KHVR. There will also be scattered showers and a few thunderstorms on Sunday, mainly over central/North-central MT between 13/20 and 14/06Z. Low VFR/MVFR conditions and localized wind gusts over 35 kts will be the primary concerns. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 42 68 46 63 / 0 20 50 10 CTB 38 57 41 57 / 0 40 30 30 HLN 43 71 44 63 / 0 30 40 0 BZN 41 78 40 64 / 0 0 50 10 WYS 36 70 26 60 / 0 0 0 0 DLN 41 76 37 65 / 0 0 0 0 HVR 38 71 45 62 / 0 0 90 50 LWT 39 72 43 59 / 0 0 60 20

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Watch from Monday morning through Monday afternoon for Fergus County below 4500ft-Snowy and Judith Mountains.

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