551 FXUS65 KTFX 041132 AFDTFXArea Forecast Discussion National Weather Service Great Falls MT 532 AM MDT Sat Oct 4 2025
Aviation Section Updated.
.KEY MESSAGES...
- A Fall storm system affects the region through the weekend with progressively cooler temperatures and lowering snow levels.
- Impactful snowfall is expected primarily in the mountains tonight through Sunday morning with some brief snow at lower elevations Sunday morning.
- Gusty north winds and much colder temperatures Sunday will be followed by a widespread hard freeze at many locations Sunday night.
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.DISCUSSION... /Issued 354 AM MDT Sat Oct 4 2025/
- Meteorological Overview:
Precipitation coverage will increase this morning across southwest MT as a closed upper level low lifts out of the Great Basin into WY. Meanwhile, larger scale upper level troughing across western Canada deepens with an initial embedded wave dropping south out of BC into the Northern Rockies today before another embedded shortwave, currently moving out of the Yukon/NWT, sends a stronger cold front south along the Rockies tonight.
Height falls and cooling aloft beneath the deepening trough will bring noticeable cooling today with afternoon high temperatures mainly in the 50s and snow levels lowering to around 7000 ft by late this afternoon. Precipitation increases late this afternoon from Glacier NP south along the continental divide ahead of the shortwave dropping south out of BC and intensifies tonight as the secondary wave and strong cold front push south from Alberta. The cold front surges south across most of north-central MT late tonight and across southwest MT Sunday morning. Snow levels rapidly fall with the cold front late tonight through Sunday morning reaching as low as around 4000 ft across portions of north-central MT and around 5500 ft across southwest MT. Precipitation spreads south with the cold front overnight and lingers across southwest MT into Sunday afternoon with higher amounts focused over the Rocky Mtn Front and adjacent plains and south through the mountains of central and southwest MT as well as areas with northerly upslope enhancement adjacent to the central MT mountains.
Gusty north winds follow the frontal passage late tonight through Sunday morning as the colder airmass originating in NW Canada slides south into the region, keeping daytime temperatures in the 40s or cooler for most areas. Precipitation will clear from north to south Sunday afternoon. The lingering cold airmass will then set the stage for the season`s first widespread freeze Sunday night, with temperatures dropping into the 20s across much of the region.
Early next week, upper-level ridging will return, bringing mainly dry conditions and temperatures near or above seasonal averages by Tuesday. Mild conditions are expected to persist through mid to late next week, despite some model differences regarding a weak upper-level disturbance moving out of the Great Basin. A larger- scale trough from the Pacific is anticipated to approach by next weekend.
- Forecast Confidence & Scenarios:
A winter storm warning remains in place for Glacier NP and adjacent areas with the spread in ensemble snow amounts decreasing, leading to higher confidence in amounts in excess of 6 inches across higher elevations in the park. This includes Logan pass where the probability for amounts in excess of 6 inches is now 60%. High resolution models also suggest the potential for a period of heavier snowfall with rates to around 1/hr possible (20-30%) late tonight in western Glacier County as the front moves south out of Alberta, which could impact US-89 from Kiowa north to the international border.
Winter Weather advisories remain in place for areas from Browning south along the Rocky Mtn Front and across the Little Belts as well as the Gallatin and Madison Ranges in southwest MT where accumulations of 4 or less are generally expected across the higher elevations. While not impactful, snow levels could briefly fall as low as around 3500ft across western portions of north- central MT Sunday morning with some wet snowfall even occurring for areas from Cut Bank south to Great Falls.
Minimum temperatures are expected to fall below freezing for all areas Sunday night with an 80% or greater probability for temperatures reaching 28F or less.
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.AVIATION... 04/12Z TAF Period
Precipitation increases across southwest MT this morning with widespread MVFR conditions and mountain obscuration there while primarily VFR conditions under mid to high level cloud-cover persists across north-central MT into this afternoon. Precipitation ahead of a frontal system moving out of western Canada increases across western portions of north-central MT late this afternoon and evening. A period of IFR/MVFR conditions in precipitation and lower clouds spreads south across the region tonight with gusty north winds also developing with the passage of the frontal system. Hoenisch
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.PRELIMINARY POINT TEMPS/POPS... GTF 58 36 47 26 / 20 80 70 0 CTB 53 30 45 22 / 60 90 30 0 HLN 58 36 46 27 / 40 90 80 10 BZN 53 35 45 24 / 70 80 80 20 WYS 48 26 43 17 / 90 70 80 30 DLN 53 32 46 25 / 40 60 50 10 HVR 62 34 52 26 / 20 30 20 0 LWT 55 34 45 24 / 50 80 70 10
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.TFX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from midnight tonight to noon MDT Sunday for East Glacier Park Region.
Winter Weather Advisory from midnight tonight to noon MDT Sunday for Little Belt and Highwood Mountains-Northern High Plains- Snowy and Judith Mountains-Southern Rocky Mountain Front.
Winter Weather Advisory from 6 PM this evening to 6 PM MDT Sunday for Gallatin and Madison County Mountains and Centennial Mountains.
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$$ http://www.weather.gov/greatfalls
NWS TFX Office Area Forecast Discussion