textproduct: Great Falls

KEY MESSAGES

- Breezy at times on Friday, especially across Southwest Montana and along the Rocky Mountain Front.

- Daily chances for afternoon showers and thunderstorms through Friday, especially along the Continental Divide.

- Temperatures will cool off over the weekend into early next week with a chance for widespread wetting precipitation.

DISCUSSION

/Issued 1215 AM MDT Thu Sep 3 2026/

- Meteorological Overview:

Southwesterly flow will persist over the region through Friday as the upper-level trough remains along the west coast. This setup will bring temperatures down slightly and allow for daily chances for afternoon showers and thunderstorms, mainly in Southwest Montana and along the Continental Divide. Breezy southwest winds will also be present during this time across the region, although it will be a far cry from what was observed on Wednesday.

Through the weekend, the closed low over the PacNW shifts slightly but maintains south/southwesterly flow over the region which will draw up more tropical moisture into Montana. On Monday, the low ejects a shortwave trough over the region which has the chance to bring more widespread wetting rain through Tuesday.

- 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 on Friday 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 70% 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

03/12z TAF Period

VFR conditions will prevail throughout the duration of the 0312/0412 TAF period; however, showers along the Continental Divide will lead to mountain obscuration beyond 00z Friday.

For KGTF: Southwest winds will turn to the west southwest through 20z this afternoon, with a 20% chance for crosswinds to exceed 15kts between 20-24z. Beyond 00z Friday winds will become light and variable, with periods of northwest to northeast winds presenting a <10% chance for crosswinds to be exceeded. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 74 49 76 48 / 0 10 0 50 CTB 66 44 66 43 / 10 30 10 60 HLN 74 47 75 48 / 0 10 20 50 BZN 75 46 79 44 / 0 0 0 10 WYS 64 36 67 37 / 0 0 0 20 DLN 72 41 74 42 / 0 10 10 20 HVR 80 50 82 48 / 0 0 0 10 LWT 77 52 82 48 / 0 0 0 10

TFX WATCHES/WARNINGS/ADVISORIES