Severe thunderstorms developed near a warm frontal zone over the lower Susquehanna valley during the late afternoon and early evening. The storms produced significant downburst wind damage with peak wind speeds between 60 and 90 mph, knocking down multiple large trees and branches. Considerable structural damage also resulted from the severe winds. Isolated large hail was reported up to one-inch in diameter. A brief EF0 tornado, embedded within a larger swath of straight-line wind damage, touched down in the Thousand Trails campground with peak winds around 80 mph.

Hail in LANCASTER, PENNSYLVANIA
From 22-JUN-10 16:03:00 to 22-JUN-10 16:03:00 (EST-5)
Location: EPHRATA
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 22-JUN-10 16:35:00 to 22-JUN-10 16:35:00 (EST-5)
Location: MECHANICS GROVE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds estimated near 60 mph toppled numerous trees and wires in East Drumore Township south of Quarryville.

Thunderstorm Wind in LEBANON, PENNSYLVANIA
From 22-JUN-10 15:35:00 to 22-JUN-10 15:35:00 (EST-5)
Location: CAMPBELLTOWN
Magnitude: 70.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

NWS meteorologists surveyed downburst/straight-line wind damage at the Bowman Farm east of Campbelltown just south of the Route 322. Significant structural damage was found including the removal of the roof and partial collapse of the second story. Several windows were shattered due to flying debris or hail. At least three other barns or outbuildings sustained damage. Maximum wind gusts were estimated around 80 mph.

Tornado in LEBANON, PENNSYLVANIA
From 22-JUN-10 15:30:00 to 22-JUN-10 15:30:00 (EST-5)
Location: FONTANA
Tornado F-scale: EF0
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A survey team from the National Weather Service in State College confirmed an EF0 tornado at the Thousand Trails Campground on 493 S. Mt. Pleasant Road in South Annville Township. The touch-down was very brief with only a 200 yard path length and 50 yard path width. The maximum winds were estimated around 80 mph. The main damage was concentrated within a wooded area near the back of the campground facility. Several trailers sustained damage from falling trees and branches. The tornado was embedded within a broader area of thunderstorm straight-line wind damage that extended approximately seven miles from just east of Hershey into southwest Lebanon County.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 22-JUN-10 16:50:00 to 22-JUN-10 16:50:00 (EST-5)
Location: LITTLE BRITAIN
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds estimated near 60 mph knocked down two outbuildings in Little Britain Township.

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 22-JUN-10 15:20:00 to 22-JUN-10 15:20:00 (EST-5)
Location: HERSHEY
Magnitude: 70.00 EG
Property damage: 20.00K
Crop damage: 20.00K
Reported by: Emergency Manager

Significant thunderstorm winds estimated between 60-80 mph damaged eight buildings at the Milton Hershey School. Numerous large trees and branches were down, some causing damage to buildings and roofs. A farm house across from the school lost its roof and two other nearby barns and outbuildings sustained significant damage. Nearly 60 acres of fruit, corn and soybean crops were destroyed.

Thunderstorm Wind in YORK, PENNSYLVANIA
From 22-JUN-10 16:00:00 to 22-JUN-10 16:00:00 (EST-5)
Location: EAST PROSPECT
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds estimated near 60 mph toppled numerous trees and wires near East Prospect.

Thunderstorm Wind in LANCASTER, PENNSYLVANIA
From 22-JUN-10 16:16:00 to 22-JUN-10 16:16:00 (EST-5)
Location: COLEMANVILLE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds estimated near 60 mph toppled numerous trees and wires in Conestoga Township near Safe Harbor.

Hail in LEBANON, PENNSYLVANIA
From 22-JUN-10 15:30:00 to 22-JUN-10 15:30:00 (EST-5)
Location: ANNVILLE
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DAUPHIN, PENNSYLVANIA
From 22-JUN-10 15:15:00 to 22-JUN-10 15:15:00 (EST-5)
Location: HERSHEY
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 22-JUN-10 15:15:00 to 22-JUN-10 15:15:00 (EST-5)
Location: HERSHEY
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds estimated near 60 mph toppled numerous large trees and wires just east of Hershey.

Thunderstorm Wind in DAUPHIN, PENNSYLVANIA
From 22-JUN-10 15:20:00 to 22-JUN-10 15:20:00 (EST-5)
Location: PALMDALE
Magnitude: 70.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Significant thunderstorm winds estimated between 60-80 mph produced widespread damage just west of Campbelltown in Derry Township. Several large trees, poles and branches were down across Route 322.