textproduct: Great Falls

KEY MESSAGES

- Rain will gradually end along the Hi-Line this evening.

- It will be dry and breezy on Wednesday and Thursday.

- Precipitation and cooler temperatures return Friday through this weekend.

DISCUSSION

/Issued 212 PM MDT Tue Sep 8 2026/

- Meteorological Overview:

An upper-level trough is moving over North-central, Central, and Southwestern Montana this afternoon. As a result rain showers will linger across the Hi-Line through this evening with cooler temperatures across the area. On Wednesday an upper-level ridge moves over North-central, Central, and Southwestern Montana. This will bring dry and warm temperatures (near seasonal averages) to the area on Wednesday. On Wednesday the pressure gradient increases which will bring breezy conditions to the Rocky Mountain Front. On Thursday the upper-level ridge begins to break down. This will keep warmer temperatures with mostly dry weather for the area on Thursday. Thursday evening a cold front will move through North- central, Central, and Southwestern Montana.

On Friday an upper-level trough is over North-central, Central, and Southwestern Montana. This combined with the cold front that moved through will bring cooler temperatures (well-below seasonal averages) to the area. On Friday there will be rain showers across North-central, Central, and Southwestern Montana. Saturday through Monday there will be an upper-level closed low that will bring cooler temperatures and widespread precipitation to the area. Higher elevation locations have the potential to receive snow this weekend. See the Forecast Confidence & Scenarios Section for details. -IG

- Forecast Confidence & Scenarios:

On Wednesday there is a 60 - 80% chance for wind gusts of 40 mph or greater. On Thursday there is greater than a 60% chance for wind gusts of 40 mph or greater across the Rocky Mountain Front and Plains west of 1-15, the Hi-Line, Cascade to Judith Basin County, and the North-South orientated valleys of Southwestern Montana. On Thursday along the Rocky Mountain Front there is a 60 - 80% chance for wind gusts of 55 mph or greater.

Saturday through Monday deterministic and ensemble models differ on the track and strength of the upper-level trough/closed-low. On Saturday two clusters have a closed upper-level low in the vicinity of Washington/Oregon. This scenario would keep temperatures similar to Friday with widespread precipitation and breezy conditions across North-central, Central, and Southwestern Montana. On Saturday one cluster has an upper-level trough over eastern Washington and Oregon. This scenario would keep similar weather to the closed low scenario but it would be slightly less windy. A third cluster has a upper-level trough over Montana. This scenario would bring cooler temperatures and widespread precipitation across North-central, Central, and Southwestern Montana. On Sunday three out of four clusters have an upper-level trough over North-central, Central, and Southwestern Montana. This scenario would bring cool temperatures and widespread precipitation to North-central, Central, and Southwestern Montana. On Sunday the fourth cluster has a closed upper-level low off the coast of Washington/Oregon with an upper- level ridge over Montana. This would bring warm and mostly dry weather to North-central, Central, and Southwestern Montana. This all shows that this weekend through Monday there is high uncertainty in the overall weather pattern. However, in whichever scenario pans out there is at least a moderate chance for snow across the higher peaks of North-central, Central, and Southwestern Montana this weekend. -IG

AVIATION

09/00Z TAF Period

High confidence in VFR conditions across all terminals with the exception of KLWT as we move into the night. Isolated showers are currently shifted east out of the region but still lingering near terminal KLWT lending to the use of a TEMPO group through 09/02z. Showers will be quick movers, but may briefly lead to degraded visibility and low cloud bases. As they shift east and weaken, the terminal may experience erratic winds. Beyond the 09/02z time frame, all terminal across the TAF period will remain VFR. Winds area wide will ramp up Wednesday afternoon as a ridge of high pressure shifts its axis over central Montana. Winds will be gusty across SW Montana and along the Rocky Mountain Front largely out of the southwest. -JR

For KGTF: VFR Conditions will prevail through the night and into Wednesday afternoon. Odds remain low (<30%) of cross winds exceeding the 15kt threshold through 09/02z but worth noting sporadic gusts may briefly exceed the threshold before dropping off to near 0% through 09/15z. As winds Begin to ramp up 09/15z and onward, direction remains favorable for flight with high confidence in headwind gusts exceeding 15kts and low probability (<10%) of crosswinds approaching the 15k threshold. -JR

PRELIMINARY POINT TEMPS/POPS

GTF 63 44 76 54 / 90 10 0 0 CTB 60 44 69 50 / 90 10 0 0 HLN 68 42 76 49 / 20 0 0 0 BZN 68 39 77 45 / 30 0 0 0 WYS 63 30 70 30 / 10 0 0 0 DLN 68 37 78 41 / 0 0 0 0 HVR 63 43 75 49 / 100 40 0 0 LWT 65 41 73 50 / 30 20 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.