textproduct: Great Falls

KEY MESSAGES

- It will be windy across North-central, Central, and Southwestern Montana this afternoon with isolated showers and thunderstorms.

- Widespread showers and isolated thunderstorms will affect North-central, Central, and Southwestern Montana Sunday through early next week.

- It will cool off this weekend though early next week.

DISCUSSION

/Issued 151 PM MDT Fri Sep 4 2026/

- Meteorological Overview:

This afternoon an upper-level closed low is over Washington and Oregon with southerly flow over North-central, Central, and Southwestern Montana. This will bring breezy winds to the area with the strongest winds in north-south orientated valleys in Southwestern Montana. There will be isolated showers and thunderstorms primarily confined along the Continental Divide this afternoon/evening. Some of these showers and thunderstorms could make it as far the I-15 corridor by this evening. It will be around seasonal averages today. On Saturday the upper-level closed low remains over Washington and Oregon with southerly flow aloft. It will remain warm and breezy on Saturday with showers and thunderstorms primarily confined to the continental divide.

On Sunday the upper-level closed low remains over Washington and Oregon with southerly flow aloft. As the upper-level low weakens and begins to slide east a shortwave moves through the upper-level trough. This will bring showers and thunderstorms to North-central Montana with stronger thunderstorms expected in Blaine and Fergus County. See the Forecast Confidence & Scenarios Section for details. On Monday the upper-level trough moves over North- central, Central, and Southwestern Montana. This will bring cooler temperatures and widespread showers and thunderstorms to the area on Monday. On Tuesday the upper-level trough begins to exit North-central, Central, and Southwestern Montana. This will allow temperatures to gradually warm up but remain below seasonal averages across the area. Rain showers will linger through the day on Tuesday. On Wednesday and Thursday an upper-level ridge builds back in over North-central, Central, and Southwestern Montana. This will allow temperatures to warm up with mostly dry weather. -IG

- Forecast Confidence & Scenarios:

On Sunday there is a 30 - 40% chance for thunderstorms along and east of a Cut Bank to Great Falls line. For Sunday the Storm Prediction Center has issued a marginal risk (5% chance for 58 mph wind gusts or greater and/or a 5% chance for hail 1 inch in diameter or greater) for severe thunderstorms northeast of a Cut Bank to Great Falls to Judith Gap line. On Monday there is a 25 - 40% chance for thunderstorms across North-central, Central, and Southwestern Montana.

From 6 am Sunday through 6 am Tuesday there is greater than a 60% chance for 2 inches of rain or greater along the Hi-Line. From 6 am Sunday through 6 am Tuesday there is a 60 - 80% chance for 1 inch of rainfall or greater across North-central Montana. From 6 am Sunday through 6 am Tuesday there is a 30 - 60% chance for half an inch of rain or greater across Central and Southwestern Montana. Deterministic models are still flip-floping with respect to where the heaviest precipitation amounts will be. -IG

AVIATION

05/00Z TAF Period

Scattered rain showers will continue through the rest of the afternoon with low confidence in impacts to any one terminal through the rest of the day. A low stratus deck will continue to build through the overnight hours as more showers start to fill in along the Continental Divide into portions of the Rocky Mountain Front. Periods of mountain obscuration are possible through the overnight hours into early Saturday afternoon. The greatest chance for precipitation will be at KCTB where periods of MVFR/IFR conditions are possible between 05/11Z and 05/21Z.

For KGTF: VFR conditions will prevail through the period with a low stratus deck expected to linger through at least the mid- morning hours on Saturday. Winds in the early afternoon will start to pick up out of the northeast with gusts up to 20kts possible. Right now there is only about a 10% chance for significant crosswinds after 05/20Z. The bulk of the showers and thunderstorms tomorrow are expected to remain along the Continental Divide and along the Rocky Mountain Front but there is a 30% chance for showers to make their way into the vicinity of KGTF after 06/00Z. -thor

PRELIMINARY POINT TEMPS/POPS

GTF 49 75 50 75 / 40 10 30 10 CTB 46 67 48 64 / 70 70 70 70 HLN 49 77 49 78 / 20 20 30 10 BZN 46 81 46 82 / 0 0 0 0 WYS 39 72 38 75 / 0 0 0 0 DLN 45 79 44 81 / 10 0 0 0 HVR 50 81 55 80 / 0 10 30 60 LWT 48 78 50 78 / 0 0 10 30

TFX WATCHES/WARNINGS/ADVISORIES

None.