131 FXUS65 KTFX 270544 AFDTFXArea Forecast Discussion National Weather Service Great Falls MT 1144 PM MDT Fri Sep 26 2025
Aviation Section Updated.
.KEY MESSAGES...
- Gusty winds are expected along the Rocky Mountain Front foothills early Saturday morning.
- Above average temperatures and dry weather continues through Sunday afternoon.
- Showers and thunderstorms return for the beginning of the week Sunday, with the best chances for precipitation over the Continental Divide and Southwest Montana.
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.UPDATE... /Issued 637 PM MDT Fri Sep 26 2025/
Given upper level ridging in place, no major changes were needed with the forecast tonight. The main adjustment was to use latest near-term guidance to fine tune mention of smoke. -AM
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.DISCUSSION... /Issued 300 PM MDT Fri Sep 26 2025/
- Meteorological Overview:
Behind the cold front passage earlier today, upper level ridging continues to build in over the next few days. Winds aloft will continue to transport smoke from the Pacific Northwest today and tomorrow. This ridging pattern will keep above normal temperatures through the weekend. Mountain wave activity over the Northern Rocky Mountain Front will bring another round of gusty winds along the foothills overnight tonight through early Saturday morning, before decreasing. On Sunday, southwest flow aloft moves in with a trough building along the Pacific Coast. Slight advection of monsoonal moisture from the Southwest will bring low end chances for isolated showers and thunderstorms along the MT/ID border. Monday, a frontal passage will bring a better coverage of precipitation for areas mainly along the Continental Divide. Precipitation spreads farther east across the North- Central Plains for Tuesday.
There is a little bit of uncertainty in how this trough continues to evolve as it passes through the state mid to late week. Some solutions keep it drier, while others keep precipitation around through the work week. Ensembles do hint at cooler temperatures settling in for the later part of next week.
- Forecast Confidence & Scenarios:
For winds overnight tonight into Saturday morning, there`s a 30-70% chance for 40 mph winds over the Rocky Montain Front Foothills, with a 50% chance for 50 mph winds along the immediate downslope of the Rockies.
For precipitation next week, the timing of the front will matter for the chances for thunderstorms in the afternoon Monday and Tuesday. Low instability will keep thunderstorms on the weaker side, but if precipitation arrives later in the evening then chances for thunderstorms diminishes. Ensembles keep the bulk of the precipitation areas closer to the Continental Divide/Southwest MT. Both days, there`s a 30-60% chance for 0.25" of rain. However, the convective nature of this system will allow for locally higher amounts with thunderstorms that get a heavier shower. -Wilson
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.AVIATION... 27/06Z TAF Period.
Overall, VFR conditions are expected across the CWA through the period. Some smoke will reduce distant visibility at times, obscuring mountains/passes through the period. Brusda
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.PRELIMINARY POINT TEMPS/POPS... GTF 46 81 46 79 / 0 0 0 0 CTB 46 76 44 72 / 0 0 0 0 HLN 45 80 46 82 / 0 0 0 0 BZN 39 78 43 81 / 0 0 0 0 WYS 29 70 32 69 / 0 0 0 10 DLN 39 76 41 78 / 0 0 0 0 HVR 45 80 46 81 / 0 0 0 0 LWT 44 79 49 81 / 0 0 0 0
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.TFX WATCHES/WARNINGS/ADVISORIES... None.
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$$ http://www.weather.gov/greatfalls
NWS TFX Office Area Forecast Discussion