textproduct: Great Falls

KEY MESSAGES

- It will be hot, dry, and hazy through Tuesday.

- A brief cool down is expected Wednesday through next Friday with isolated showers returning.

- Next weekend there will be isolated showers and thunderstorms with warmer temperatures.

DISCUSSION

/Issued 257 PM MDT Sun Aug 9 2026/

- Meteorological Overview:

This afternoon there is an upper-level ridge over North-central, Central, and Southwestern Montana. This will bring slightly cooler temperatures to the area with dry weather. On Monday and Tuesday the upper-level ridge remains over North-central, Central, and Southwestern Montana. This will will keep warm and dry weather for the area on Monday and Tuesday. Smoke from regional wildfires will be around throughout the next few days. On Wednesday the upper-level ridge remains over North-central, Central, and Southwestern Montana with an upper-level trough approaching the area. This will begin to bring cooler air and monsoonal moisture to the area on Wednesday.

Thursday through Friday an upper-level trough moves over North- central, Central, and Southwestern Montana. This will bring precipitation chances and cooler temperatures (well-below seasonal averages) to the area Thursday through Friday. See the Forecast Confidence & Scenarios section for details. Next weekend an upper- level ridge builds back in over North-central, Central, and Southwestern Montana with southwest flow aloft. This will bring daily chances for showers and thunderstorms with temperatures warming up on Saturday and next Sunday. -IG

- Forecast Confidence & Scenarios:

Today and tomorrow across North-central, Central, and Southwestern Montana minimum afternoon humidity will be near critical levels. This combined wind gusts that will peak at around 20 mph will bring elevated fire weather conditions to the area. The wind direction will also periodically shift over the next 24 to 48 hours. The greatest risk for elevated to near critical fire weather conditions is in Southwestern Montana this afternoon through Tuesday.

Wednesday through Friday there are differences in the track of the upper-level trough in ensembles and deterministic models. On Thursday and Friday one cluster has zonal flow over Montana while the other three have an upper-level trough approaching Montana. In the zonal flow scenario temperatures will remain at about seasonal averages with a few isolated showers. In the upper-level trough scenario temperatures will cool off to at least below seasonal averages with more widespread showers. Another area of uncertainty with this trough is how far south it tracks. The further south it tracks, the further south the precipitation will be and it will result in cooler temperatures than a more northerly track.

On Wednesday there is a 30 - 45% chance for thunderstorms across the Hi-Line and a 20 - 30% chance for thunderstorms across the rest of North-central, Central, and Southwestern Montana. On Thursday there is a 20 - 40% chance for thunderstorms across most of North-central, Central, and Southwestern Montana. On Friday there is a 35% chance for thunderstorms across Central and Southwestern Montana. Wednesday through Friday there is a 40 - 80% chance for a quarter inch of rain or greater across North- central, Central, and Southwestern Montana with the highest probabilities along the Hi-Line. Wednesday through Friday there is a 50 - 70% chance for one half inch or rain or greater along the Hi-Line and across Choteau, Judith Basin, and Fergus Counties. On Thursday and Friday there is greater than a 50% chance for high temperatures of 70 degrees or lower across the plains of North- central Montana. -IG

AVIATION

10/00Z TAF Period

Initial concern will be for continued wildfire smoke reducing both slant-range and surface visibility across the region. The smoke looks to remain most dense across SW MT and vicinity through the TAF period. A few showers or thunderstorms cannot be ruled out across the Hi-Line and adjacent areas tomorrow afternoon, but the probability of these occurring at a terminal was too low to include mention at this time.

For KGTF: Probability of a 15kt crosswind will remain essentially zero through the morning Monday. There is lower than average confidence in the wind direction by Monday afternoon, with the most aggressively mixed scenarios resulting in a westerly wind by early afternoon, with occasional gusts in excess of 20 kts. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 54 89 54 84 / 0 0 0 0 CTB 51 81 50 77 / 0 0 0 10 HLN 55 90 54 88 / 0 0 0 0 BZN 52 87 52 89 / 0 0 0 0 WYS 44 81 42 86 / 0 0 0 0 DLN 51 87 50 89 / 0 0 0 0 HVR 53 88 52 84 / 0 0 0 0 LWT 52 86 52 82 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.