801 FXUS65 KTFX 242054 AFDTFXArea Forecast Discussion National Weather Service Great Falls MT 254 PM MDT Wed Sep 24 2025
.KEY MESSAGES...
- Afternoon high temperatures will soar as high as 15 to 20 degrees above average through Thursday.
- Periods of breezy to windy conditions are expected through Saturday, especially along the Rocky Mountain Front.
- Temperatures cool slightly on Friday and then rebound once again early next week.
- Scattered shower and thunderstorm activity returns by Monday.
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.DISCUSSION...
- Meteorological Overview:
Strong ridging aloft will maintain late summer/early autumn heat over the Northern Rockies for the next 24 hours before a fast moving Pacific trough brings a brief cool down on Friday. Other than increased mid- to high level cloudiness and the aforementioned cooler temperatures Thursday night into Friday, the primary concern will be very warm, dry, and breezy to windy conditions, especially on Thursday when southwesterly winds increase in response to the approaching trough and afternoon temperatures peak well into the 80s.
The ridge aloft rebuilds over the weekend, despite continued elevated westerly flow aloft. The stronger winds aloft will relax after Saturday, but not before mountain wave activity brings a period of 40 to 60 mph winds along the Rocky Mountain Front Friday night into early Saturday.
Southwesterly flow aloft develops over the Northern Rockies by Monday in response to a trough moving into the Pacific Northwest. This will result in increased shower and thunderstorm activity while temperatures remain above average through mid- week. - RCG
- Forecast Confidence & Scenarios:
Very warm, dry, and or breezy to windy conditions through Saturday...
Lower elevation high temperatures warming well into the 80s and increased westerly breezes will be the primary concern for the next couple of days. The driest and windiest conditions are expected along the Rocky Mountain Front and the adjacent high plains west of I15 on Thursday. These areas will see minimum relative humidity values falling into the teens while winds gust over 30 mph at times. Despite the windy and dry conditions, energy release component values well below the 90th percentile are expected to preclude widespread elevated fire weather concerns.
The windier conditions expand to include most of central and north- central MT on Friday with probabilities for gusts over 35 mph increasing to the 40 to 60% range. The elevated fire risk should be on the low side on Friday given the strongest winds looking to occur earlier in the day and afternoon temperatures cooling 10 to 15 degrees cooler from Thursday`s highs. Mountain wave activity will bring more windy conditions to the Rocky Mountain Front and adjacent high plains Friday night into early Saturday with areas along and west of the highway 89 corridor currently having a greater than 50% chance for 50 mph wind gusts.
Increased shower and thunderstorm activity Monday through next Wednesday...
A more active southwesterly flow aloft will bring increased shower and thunderstorm activity early next week. Areas along the Continental Divide and Southwest Montana should see the most rainfall where probabilities for totals over a quarter inch are running between 50 and 70% for the 72 hour period ending next Thursday at 6 am. The general unsettled conditions are expected to continue into the second half of next week. - RCG
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.AVIATION... 24/18Z TAF Period
Ridging aloft will maintain mostly clear skies and VFR conditions over the next couple of days. A weak cold front will bring a northerly wind shift to the plains terminals between 24/21 and 25/03Z before winds become light and variable during the overnight hours. Winds become south to southwesterly in response to an approaching trough on Thursday and may gust over 30 kts at times, mostly along the Rocky Mountain Front and near the KCTB area. - RCG
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.PRELIMINARY POINT TEMPS/POPS... GTF 46 86 51 75 / 0 0 0 0 CTB 40 84 46 69 / 0 0 0 0 HLN 47 84 50 74 / 0 0 0 0 BZN 43 83 44 74 / 0 0 0 0 WYS 29 71 33 69 / 0 0 0 0 DLN 40 79 42 74 / 0 0 0 0 HVR 44 83 48 73 / 0 0 0 0 LWT 47 84 51 72 / 0 0 0 0
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.TFX WATCHES/WARNINGS/ADVISORIES... None. &&
$$ http://www.weather.gov/greatfalls
NWS TFX Office Area Forecast Discussion