textproduct: Great Falls

KEY MESSAGES

- Drier today with decreasing clouds and seasonable temperatures by this afternoon.

- Showers and a few thunderstorms develop late Friday with a cold front that brings cooler temperatures and another round of showers into Saturday.

- Warmer and drier weather develops early next week.

UPDATE

/Issued 712 AM MDT Thu Jun 11 2026/

Northwest flow aloft behind departing troughing is resulting in showers lingering a bit longer than prior thinking. As such, probability for precipitation was increased through the remainder of the morning, primarily over the plains east of I-15. No other changes made at this time. -AM

DISCUSSION

/Issued 712 AM MDT Thu Jun 11 2026/

- Meteorological Overview:

Upper level troughing shifts east into the Northern US Plains states today with a drier WNW flow aloft developing in its wake across MT. Early morning clouds and showers lingering near the central MT mountains will exit by late morning with mainly dry and seasonably warm conditions across the the area by this afternoon. Afternoon instability and residual moisture may lead to some isolated shower and thunderstorm development with areas along and north of US-2 most likely to see some of this activity through early this evening.

After a dry start on Friday the risk for showers and thunderstorms increases again Friday afternoon as the next shortwave in NW flow moves into the Northern Rockies from BC with another disturbance dropping south from AB across the area Friday night through Saturday. A cold front moves south across the area later Friday through Friday night, providing enough cooling to lower snow levels as low as 6500 ft across the central MT mountains with showers continuing through Saturday morning. Surface high pressure (~1025MB) also slides south behind the front Friday night with a period of gusty north winds likely as this moves south across the Plains Friday evening and through the SW MT Valleys Friday night.

Longer range model consensus amplifies upper ridging through BC Sunday and Monday, resulting in mainly dry conditions with temperatures warming above seasonal averages early next week. This does look to de-amplify later next week with the warmest temperatures peaking on Tuesday. Hoenisch

- Forecast Confidence & Scenarios:

High resolution models key on a few thunderstorms developing Friday afternoon across western portions of north-central MT with scattered showers and storms tracking ESE through Friday evening. Instability/CAPE is marginal (<1000J/Kg) but fast mid level winds and the timing of a Canadian cold front Friday afternoon/evening could support some stronger wind gusts with cells.

After a relatively cool day Saturday, decreasing clouds Saturday night will allow overnight temperatures to reach the mid-upper 30s for many locations. There is 30-50% probability for minimum temperatures of 36F of less at Bozeman, Dillon, Lewistown and Cut Bank with lower (10-15%) probabilities at Helena, Great Falls and Havre. Hoenisch

AVIATION

11/18Z TAF Period

Primary concern this TAF period will be for scattered showers and a few thunderstorms this afternoon, mainly over the plains of North- central Montana east of I-15. Breezy westerly winds diminish around sunset. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 71 44 70 40 / 20 0 40 80 CTB 67 41 62 35 / 20 0 80 60 HLN 72 44 74 42 / 10 0 0 60 BZN 70 39 74 38 / 10 0 0 40 WYS 62 29 70 31 / 10 0 0 0 DLN 71 38 76 37 / 10 0 0 10 HVR 70 43 67 37 / 30 20 50 20 LWT 66 40 66 37 / 20 0 20 70

TFX WATCHES/WARNINGS/ADVISORIES

None.