textproduct: Great Falls

KEY MESSAGES

- There will be isolated showers this afternoon and evening with showers and thunderstorms in Southwestern Montana Monday afternoon/evening.

- It will be windy on Tuesday across North-central Montana.

- Monday through Friday it will warm up to around seasonal averages with mostly dry weather.

DISCUSSION

/Issued 117 PM MDT Sun Sep 27 2026/

- Meteorological Overview:

This afternoon an upper-level ridge begins to build in over North- central, Central, and Southwestern Montana. This will keep cool temperatures over the area. An upper-level shortwave will move through the upper-level flow this afternoon and evening and bring showers and thunderstorms to Southwestern Montana. This evening isolated showers will spread to North-central Montana. On Monday a weak upper-level trough moves over North-central, Central, and Southwestern Montana. This will bring showers and thunderstorms to Southwestern Montana on Monday. It will warm up across the area with mostly dry weather north of I-90 on Monday.

On Tuesday there will be zonal (west to east) flow over North- central, Central, and Southwestern Montana. This will allow warm temperatures to remain with dry weather. On Tuesday there will be strong low-level and mid-level winds. This will bring windy conditions to North-central Montana with the strongest winds along the Rocky Mountain Front. On Wednesday zonal flow remains over North-central, Central, and Southwestern Montana with strong low- level and mid-level winds. This will bring warm and mostly dry weather to the area with windy conditons across North-central Montana. On Thursday and Friday an upper-level ridge builds in over North-central, Central, and Southwestern Montana. This will allow temperatures to warm up with mostly dry weather across the area. -IG

- Forecast Confidence & Scenarios:

On Monday there is a 20 - 30% chance for thunderstorms across southern Gallatin and Madison Counties. On Monday there is a 40 - 60% chance for a quarter inch of rain or greater in the West Yellowstone area. On Tuesday across the Northern Rocky Mountain Front there is a 40 - 70% chance for wind gusts of 75 mph or greater. On Tuesday across the plains west of I-15 there is a a 20 - 50% chance for wind gusts of 55 mph or greater. As a result a High Wind Watch was issued for the northern Rocky Mountain Front and northern High Plains from 12 AM Tuesday to 12 AM Wednesday. -IG

AVIATION

28/00Z TAF Period.

An elongated Pacific trough will bring variable cloudiness and scattered showers/light stratiform rain tonight into Monday. The most widespread precipitation and low VFR/MVFR flight degradations will be south of the I90 corridor roughly between 28/08 and 28/16Z, especially for the KWYS area. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 45 73 45 73 / 30 0 0 0 CTB 36 67 42 65 / 10 0 0 0 HLN 42 71 40 74 / 20 0 0 0 BZN 38 68 37 74 / 10 20 0 0 WYS 37 60 28 66 / 70 50 20 0 DLN 40 68 36 75 / 10 0 0 0 HVR 41 72 42 75 / 20 0 0 0 LWT 41 70 41 76 / 10 10 0 0

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Watch from late Monday night through Tuesday evening for East Glacier Park Region-Northern High Plains.