Scattered thunderstorms developed along and ahead of a Pacific cold front and shortwave trough during the afternoon and evening of June 21st. Moderate instability and vertical wind shear allowed multiple storms to become severe, resulting in numerous reports of severe wind gusts and several instances of severe hail.

Thunderstorm Wind in MADISON, MONTANA
From 21-JUN-18 13:34:00 to 21-JUN-18 13:34:00 (MST-7)
Location: ENNIS
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station in Ennis recorded 65-mph peak gust from thunderstorm.

Thunderstorm Wind in MADISON, MONTANA
From 21-JUN-18 13:09:00 to 21-JUN-18 13:09:00 (MST-7)
Location: CAMERON
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station 2-miles SSW of Cameron recorded 59-mph peak gust from thunderstorm.

Thunderstorm Wind in MADISON, MONTANA
From 21-JUN-18 13:43:00 to 21-JUN-18 13:43:00 (MST-7)
Location: CAMERON
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station 22-miles SW of Cameron recorded 58-mph peak gust from thunderstorm.

Thunderstorm Wind in MEAGHER, MONTANA
From 21-JUN-18 15:20:00 to 21-JUN-18 15:20:00 (MST-7)
Location: WHITE SULPHUR SPGS
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

White Sulphur Springs Airport AWOS recorded 59-mph peak gust from collapsing thunderstorm.

Hail in FERGUS, MONTANA
From 21-JUN-18 16:01:00 to 21-JUN-18 16:01:00 (MST-7)
Location: FORESTGROVE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Facebook video of hail up to quarter-size falling 10-miles WSW of Forestgrove.

Hail in FERGUS, MONTANA
From 21-JUN-18 16:10:00 to 21-JUN-18 16:10:00 (MST-7)
Location: FORESTGROVE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported half dollar-size hail and broken windows on north side of buildings 8-miles W of Forestgrove. Time estimated from radar.

Thunderstorm Wind in GALLATIN, MONTANA
From 21-JUN-18 13:44:00 to 21-JUN-18 13:44:00 (MST-7)
Location: BIG SKY
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station 5-miles WSW of Big Sky recorded 65-mph peak gust from thunderstorm. Elevation: 8622 feet MSL.

Thunderstorm Wind in JEFFERSON, MONTANA
From 21-JUN-18 14:22:00 to 21-JUN-18 14:22:00 (MST-7)
Location: BOULDER
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station in Boulder reported 58-mph peak gust from thunderstorm.

Hail in FERGUS, MONTANA
From 21-JUN-18 15:52:00 to 21-JUN-18 15:52:00 (MST-7)
Location: LEWISTOWN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported quarter-size hail and wind gusts up to 50 mph from thunderstorm 6-miles ESE of Lewistown.

Thunderstorm Wind in FERGUS, MONTANA
From 21-JUN-18 16:10:00 to 21-JUN-18 16:10:00 (MST-7)
Location: FORESTGROVE
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public report of roof ripped off barn by wind gusts from thunderstorm 8-miles W of Forestgrove. Time estimated from radar.