A line of strong to severe thunderstorms formed in the warm sector of the Susquehanna Valley and moved through southeast Pennsylvania during the late afternoon and first half of the evening on the 9th. The line also spawned an EF-1 tornado in Berks County. During the evening the line of thunderstorms also caused flash flooding.  A warm front lifted northeast into the Lehigh Valley during the afternoon of the 9th. This permitted sufficient daytime heating preceding an approaching cold front. In addition, there was enough shear in the atmosphere for a tornado to occur.

Tornado in BERKS, PENNSYLVANIA
From 09-JUL-15 17:40:00 to 09-JUL-15 17:41:00 (EST-5)
Location: JALAPPA
Tornado F-scale: EF1
Property damage: 750.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An EF1 tornado occurred in Tilden Township in Berks County and injured one person.  The tornado touched down near Stone Road and moved eastnortheast, passing through the Blue Mountain Academy before crossing Mountain Road into a campground area before lifting.  The most significant damage occurred to the Blue Mountain Elementary School. The roof of the school was completely removed by the tornado. The building is a total loss.  The 52-year-old principal inside the school at the time of the tornado was injured and was found covered by ceiling tiles.  Pieces of the roof were found hundreds of yards away in trees.  Hardwood trees were snapped along the tornado's path with a soybean field having debris dragged through it with visible arcing marks.
The estimated path length of the EF-1 tornado was three-quarters of a mile with a maximum path width of 75 yards.  The estimated maximum wind speed was 105 mph.

Thunderstorm Wind in CHESTER, PENNSYLVANIA
From 09-JUL-15 17:50:00 to 09-JUL-15 18:25:00 (EST-5)
Location: HONEY BROOK
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A line of severe thunderstorms tore down numerous trees and wires across the northern tier of Chester County.

Thunderstorm Wind in MONTGOMERY, PENNSYLVANIA
From 09-JUL-15 18:05:00 to 09-JUL-15 18:40:00 (EST-5)
Location: POTTSTOWN
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A line of strong to severe thunderstorms tore down trees and wires across the northeast half of Montgomery County.

Thunderstorm Wind in LEHIGH, PENNSYLVANIA
From 09-JUL-15 18:48:00 to 09-JUL-15 18:48:00 (EST-5)
Location: COOPERSBURG
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The gust front of a severe thunderstorm damaged the gym roof and scoreboards at DeSales University in Upper Saucon Township.

Thunderstorm Wind in PHILADELPHIA, PENNSYLVANIA
From 09-JUL-15 19:18:00 to 09-JUL-15 19:18:00 (EST-5)
Location: PHILADELPHIA
Magnitude: 50.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Social Media

A severe thunderstorm knocked down a very large tree within Washington Square Park.

Thunderstorm Wind in BERKS, PENNSYLVANIA
From 09-JUL-15 17:22:00 to 09-JUL-15 17:22:00 (EST-5)
Location: REHRERSBURG
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A severe thunderstorm knocked down trees and wires that damaged five homes in Rehrersburg (Tulpehocken Township).

Thunderstorm Wind in CHESTER, PENNSYLVANIA
From 09-JUL-15 18:20:00 to 09-JUL-15 18:45:00 (EST-5)
Location: OXFORD
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Another segment of a line of severe thunderstorms tore down numerous trees and wires across the southern tier of Chester County.

Thunderstorm Wind in MONTGOMERY, PENNSYLVANIA
From 09-JUL-15 18:30:00 to 09-JUL-15 18:30:00 (EST-5)
Location: PLYMOUTH VLY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A severe thunderstorms tore down large tree limbs at the intersection of DeKalb and Germantown Pikes in Norristown.

Thunderstorm Wind in DELAWARE, PENNSYLVANIA
From 09-JUL-15 18:52:00 to 09-JUL-15 19:20:00 (EST-5)
Location: MARKHAM
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A line of severe thunderstorms tore down trees and wires in several locations throughout Delaware County. This included one downed tree that snapped a utility pole in Media.