textproduct: Great Falls

KEY MESSAGES

- Scattered showers and isolated thunderstorms late this afternoon into overnight hours, mainly SW MT.

- Above average temps through Friday.

- Upper level trough will bring cooler and windier weather during the upcoming weekend.

DISCUSSION

/Issued 611 PM MDT Tue Sep 22 2026/

- Meteorological Overview:

An upper level ridge will allow for above average temps and southwesterly flow to persist across MT through Friday. Due to an upper level disturbance, there will be scattered showers and weak thunderstorms late this afternoon into the overnight hours, mainly impacting SW MT. Additionally, high clouds will continue to spread northward as the day progresses. Warm temperatures will peak for most of MT on Thursday and Friday. Although temps will be above average for this time of year, they will remain well below record levels. ESH

A relatively strong Pacific cold front is forecast to traverse the northern Rockies late Friday into Friday night. However, model discrepancies persist regarding the precise timing and intensity of the embedded shortwave as it lifts northeastward from the Northern Rockies into AB by Saturday morning. Gusty southwest winds are likely to precede the front late Friday with showers and potentially some thunderstorms accompanying the frontal passage, followed by gusty west winds and cooler temperatures for the weekend. Hoenisch

- Forecast Confidence & Scenarios:

Due to cape values remaining mainly under 500 J/kg, thunderstorm threats will be primarily limited to isolated lightning strikes and brief gusty winds this afternoon and evening.

Looking towards the weekend, the main concern will be stronger winds along the Rocky Mountain Front and adjacent areas Friday afternoon through Saturday morning due to the approaching upper level trough and cold front. Strongest winds for the Rocky Mountain Front are currently expected Friday night with a 30-40% chance of gusts 55 mph or above. During that same time frame, there is a 10-20% of gusts exceeding 70 mph. ESH

AVIATION

23/06Z TAF Period.

VFR conditions will prevail for most terminals throughout the entries TAF period. Lingering showers will continue to move east across southwest Montana with terminals KEKS and KWYS seeing the highest confidence between 23/06z and 23/08z before precipitation exits. Attention remains in Southwest Montana as areas of patchy fog look possible, especially in locations where rain does fall and clouds thin quickest. Terminal KWYS remains of particular concern especially after 23/12z. Elsewhere, winds will pick up in the early afternoon, especially at KCTB and across the Hi- Line. They should remain steady through the end of the TAF period. -JR

PRELIMINARY POINT TEMPS/POPS

GTF 80 52 79 50 / 0 0 0 0 CTB 77 48 73 46 / 0 0 0 0 HLN 77 50 77 47 / 10 10 0 0 BZN 75 48 73 45 / 0 20 0 0 WYS 66 36 64 30 / 10 60 10 0 DLN 73 44 73 42 / 0 40 0 0 HVR 80 50 80 48 / 0 0 10 0 LWT 79 51 76 49 / 0 20 10 0

TFX WATCHES/WARNINGS/ADVISORIES

None.