An approaching cold front along with strong surface heating over the mountains allowed for the development of thunderstorms across the Billings Forecast Area.  The combination of 40-50kt largely unidirectional west/southwest layer wind profiles and steep low to mid level lapse rates resulted in bowing segments and embedded supercells that produced high winds and large hail.

Hail in STILLWATER, MONTANA
From 03-JUL-11 16:55:00 to 03-JUL-11 16:55:00 (MST-7)
Location: WHEAT BASIN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:15:00 to 03-JUL-11 17:15:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:16:00 to 03-JUL-11 17:16:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

There were numerous reports of tree branches down and power outages throughout Billings.

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:18:00 to 03-JUL-11 17:18:00 (MST-7)
Location: BILLINGS
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:56:00 to 03-JUL-11 17:56:00 (MST-7)
Location: NEWTON GROVE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Four inch diameter limbs were broken off trees.

Thunderstorm Wind in ROSEBUD, MONTANA
From 03-JUL-11 19:40:00 to 03-JUL-11 19:40:00 (MST-7)
Location: ASHLAND
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An estimated wind gust of 60 mph was reported 3 miles southeast of Ashland.

Thunderstorm Wind in POWDER RIVER, MONTANA
From 03-JUL-11 19:42:00 to 03-JUL-11 19:42:00 (MST-7)
Location: SONNETTE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Wind gusts of 60 mph were estimated 8 miles northeast of Ashland.

Thunderstorm Wind in POWDER RIVER, MONTANA
From 03-JUL-11 19:52:00 to 03-JUL-11 19:52:00 (MST-7)
Location: SONNETTE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A wind gust of 70 mph was estimated 18 miles southwest of Volborg.

Thunderstorm Wind in ROSEBUD, MONTANA
From 03-JUL-11 20:40:00 to 03-JUL-11 20:40:00 (MST-7)
Location: FORSYTH
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A wind gust of 70 mph was estimated in Forsyth.

Thunderstorm Wind in BIG HORN, MONTANA
From 03-JUL-11 18:20:00 to 03-JUL-11 18:20:00 (MST-7)
Location: WYOLA
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Two 15 diameter trees were blown down on a car.

Thunderstorm Wind in ROSEBUD, MONTANA
From 03-JUL-11 19:00:00 to 03-JUL-11 19:00:00 (MST-7)
Location: FORSYTH
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous 6-10 diameter tree limbs were reported broken along with several uprooted trees.

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:12:00 to 03-JUL-11 17:12:00 (MST-7)
Location: (BIL)LOGAN ARPT BILL
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in PARK, MONTANA
From 03-JUL-11 16:34:00 to 03-JUL-11 16:34:00 (MST-7)
Location: LIVINGSTON
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Local law enforcement reported downed trees and power lines in Livingston.

Thunderstorm Wind in YELLOWSTONE, MONTANA
From 03-JUL-11 17:15:00 to 03-JUL-11 17:15:00 (MST-7)
Location: BILLINGS
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee