A powerful thunderstorm moved across Rosebud and Custer Counties during the late afternoon and early evening hours of the 18th. Large hail and significant wind damage was reported in the Forsyth and Miles City areas.
Damage occurred on/near I-94 between exits 135 and 148. A speed limit sign was blown from its pole and carried 20 yards at exit 135. A large blue services road sign was snapped in the middle and blown backwards. Some of the 2ft sheets of metal from the sign were not found. HRH Hospital light pole signs were damaged. About 1.5 miles east on I-94 another large green route sign was snapped in half and 2ft sheets of metal from the sign were blown across the interstate and into a fence. In addition, about 1/4 mile SSE of exit 141, a power pole was snapped about midway-up and appeared to be suspended in the wire. A distribution and transmission pole just outside of Miles City were reported to be broken. Five miles further east on Curcher Road, an approximate 80ft tree with a diameter of around 5ft was uprooted and fell across a ditch crushing a fence. About 1/2 half mile to the east of that location, a billboard was removed of 1/2 of its panels and they were sent in random pieces across the ditch toward the interstate. One mile east on I-94 another billboard was completely flattened; the four supporting poles were snapped off at ground level. Approximately two miles west of exit 148 on I-94, a billboard was missing a couple of approximately 7 foot tall wooden panels.
Extensive property damage was also reported along U.S Highway 12 just east of Miles City. High winds damaged several businesses and residences and brought down numerous large trees. A roof was taken off part of a home just east of Miles City along Highway 12 as well. In addition to the roof damage, the wind brought down a large cottonwood tree and pushed a boat across the yard. Across the highway, the Cenex Harvest States Seed Plant sustained significant damage. Debris from a building on top of the plant was scattered all the way across a neighboring pasture. In addition, several trailers were damaged at Big Sky Campground.

Hail in ROSEBUD, MONTANA
From 18-JUL-10 16:44:00 to 18-JUL-10 16:44:00 (MST-7)
Location: FORSYTH
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in ROSEBUD, MONTANA
From 18-JUL-10 16:50:00 to 18-JUL-10 16:50:00 (MST-7)
Location: FORSYTH
Magnitude: 1.75 
Reported by: Trained Spotter

The hail was reported along I-94 at mile marker 98.

Thunderstorm Wind in CUSTER, MONTANA
From 18-JUL-10 17:03:00 to 18-JUL-10 17:03:00 (MST-7)
Location: MILES CITY
Magnitude: 62.00 MG
Reported by: ASOS

Thunderstorm Wind in CUSTER, MONTANA
From 18-JUL-10 17:20:00 to 18-JUL-10 17:20:00 (MST-7)
Location: MILES CITY
Magnitude: 70.00 EG
Property damage: 60.00K
Reported by: Trained Spotter

Please see Episode Narrative.

Hail in ROSEBUD, MONTANA
From 18-JUL-10 16:42:00 to 18-JUL-10 16:42:00 (MST-7)
Location: FORSYTH
Magnitude: 1.00 
Reported by: Trained Spotter

Thunderstorm Wind in CUSTER, MONTANA
From 18-JUL-10 17:06:00 to 18-JUL-10 17:06:00 (MST-7)
Location: MILES CITY
Magnitude: 70.00 EG
Property damage: 60.00K
Reported by: Law Enforcement

Please see Episode Narrative.