textproduct: Great Falls

KEY MESSAGES

- Breezy at times for SW Montana through Sunday. On Monday, breezy winds become widespread and continue through Tuesday.

- Chance for areas of showers and thunderstorms, particularly along the Continental Divide, through Sunday. More widespread steadier showers move in Sunday night and continue through Monday evening.

- Temperatures will continue to trend cooler through the beginning of next week.

DISCUSSION

/Issued 540 PM MDT Thu Sep 3 2026/

- Meteorological Overview:

Southwesterly flow will persist in the region through the weekend as the upper-trough continues to sit over the west coast. This will allow temperatures to cool down in Central and North-Central MT through the weekend. This set-up will allow for afternoon showers and thunderstorms, mainly in South western Montana and along the Continental Divide. Additionally, there will be breezy southwest winds present, mainly impacting Southwestern Montana.

As the upper-level low moves west Sunday night into Monday, widespread breezy winds will develop and continue through Tuesday. In addition, the upper-level low shifting will likely bring widespread showers Sunday night through Monday evening. For Sunday night and Monday afternoon, there is also the chance for widespread thunderstorms. As the upper-level low moves northwest and out of the region, the showers will taper off over Tuesday night. -EH

- Forecast Confidence & Scenarios:

Winds on Thursday and Friday:

Breezy southwesterly winds will be possible across Southwest Montana this afternoon with afternoon relative humidity in the 20s expected. This will keep fire weather concerns elevated for portions of Southwest Montana where a Red Flag Warning remains in effect through the evening. While stronger winds are possible along north-south oriented valleys including Ennis, there is low confidence in reaching high wind criteria with gusts expected to max out at around 45 mph. Across the rest of the plains and Central Montana, gusts between 25 and 35 mph are likely but much stronger gusts are not expected. A similar setup is expected tomorrow with scattered thunderstorms possible which may bring locally stronger wind gusts.

Rain Sunday through Tuesday:

Based on the latest model guidance, precipitation starts to fill in across the region Sunday morning into the afternoon with the heaviest moisture expected on Monday as the shortwave passes through. Lingering showers will continue through Tuesday morning and taper off from south to north through the afternoon. There is still uncertainty regarding precipitation amounts but right now the Hi- Line is the most favored for higher amounts while Southwest Montana is more favored for the low-end amounts.

Over the 48 hour period covering Sunday morning through Tuesday morning...

- For amounts greater than 0.1" there is a 80% probability of occurrence across the region.

- For amounts greater than 0.5" there is a 75% probability of occurrence north of a line between Helena and White Sulphur Springs and a 50% chance south of that line.

- For amounts greater than 1.0" there is a 50% probability of occurrence north of a line between Helena and White Sulphur Springs and a 25% chance south of that line.

- For amounts greater than 1.5" there is a 40% probability of occurrence north of a line between Great Falls and Lewistown and a less than 15% chance south of that line.

Exact amounts are likely to change but there is increasing confidence that this shortwave will at least bring minor relief to some of the recent fire weather concerns. -thor

AVIATION

04/00Z TAF Period

VFR conditions will prevail through the TAF period. Winds will be gusty at times across Southwest Montana, especially at KEKS where gusts are expected to max out at around 35kts Friday morning/afternoon. There may also be a brief period of LLWS at KWYS in the early morning before daytime mixing kicks in. Once daytime mixing begins to mix these to the surface, expect gusty winds but lessening LLWS. thor/Ludwig

For KGTF: Light northerly winds are expected to prevail through the rest of the evening and into the overnight hours. In the early morning hours winds will gradually shift to the west before picking up to around 8-10kts out of the southwest after 04/17Z. There is less than a 10% chance for exceeding the crosswind threshold over the next 24 hours, as winds will be aligned with the runway. -thor/Ludwig

PRELIMINARY POINT TEMPS/POPS

GTF 78 48 74 47 / 0 30 10 30 CTB 69 45 64 42 / 10 60 40 60 HLN 77 47 76 49 / 10 40 10 10 BZN 81 44 81 45 / 0 0 0 0 WYS 70 38 73 37 / 0 0 0 0 DLN 77 42 79 43 / 0 0 0 0 HVR 84 49 81 49 / 0 0 10 40 LWT 84 48 79 49 / 0 0 0 10

TFX WATCHES/WARNINGS/ADVISORIES

None.