A quasi-linear convective system (QLCS) raced across southeastern Pennsylvania during the late evening hours, producing significant storm-related damage across southwest and south-central Lancaster County. The thin line of low-topped thunderstorms developed in a convective environment characterized by weak instability and strong wind shear. A weak surface wave near BWI along a north-south cold front aided in the threat of damaging winds and embedded weak tornadoes along the QLCS.
An extensive ground and aerial storm survey was conducted on October 20, 2012. The survey team consisted of NWS meteorologists along with Lancaster County emergency management officials, local township coordinators and private weather consultant Dr. John Scala. The PSP provided the helicopter for the aerial portion of the storm survey.
The survey concluded that an embedded EF1 tornado in straight-line winds gusting to 100 to 110 mph occurred at multiple locations along a line of storm damage from near Fernglen in Drumore Township northeastward for over 16 miles to near Paradise in Paradise Township from approximately 2000 to 2025 EDT. From the air, an estimated 50 structures appeared to have significant damage especially to roofs.  Several barns were completely collapsed. Along the storm damage path, swaths of trees were leveled especially those along the hillsides of valleys and within ravines. As a conservative estimate, several thousand trees were downed. The tree damage had mostly a SW to NE orientation except in areas where tornadic convergence and circulation were evident.
The Lancaster EMA estimated between 5-7 million dollars in damages related to the EF1 tornado. There were 15 people injured by the tornado who were standing under an open-air pavilion at Paradise Park.

Tornado in LANCASTER, PENNSYLVANIA
From 19-OCT-12 19:00:00 to 19-OCT-12 19:25:00 (EST-5)
Location: FISHING CREEK
Tornado F-scale: EF1
Property damage: 6.00M
Reported by: NWS Storm Survey

The National Weather Service in State College, PA along with Lancaster County Emergency Management officials conducted a storm survey in the southwestern part of Lancaster County. The survey confirmed an EF1 tornado affected portions of southwest and south-central Lancaster County during the late evening on October 19, 2012.  Maximum winds were estimated between 100 and 110 mph.  The path length was approximately 16 miles and the maximum width was 200 yards.
The tornado first touched down near Fern Glen in southwest Lancaster County, then
traveled northeast to near Paradise. The tornado damage was sporadic and embedded within a larger area of straight line wind damage that extended from Fern Glen in Drumore Township to Paradise City in Paradise Township. It is estimated that the tornado touched down around 2000 pm EDT, skipped along to the northeast and lifted back up for the final time at around 2025 pm EDT. The damage path was not c continuous, as the tornado touched down and lifted up a number of times.
The locations with the most recognizable tornadic signature damage from the air were as follows from south to north: 1) Near Fernglen with evidence of strong convergent storm damage 2) Near Liberty Square with a clearly-defined convergent wind pattern in the corn field and nearby tree and structure damage 3) About 1.5 miles southwest of Buck where 3 medium-sized high tension electric transmission towers were knocked down from south to north 4) About 2 miles west-northwest of Quarryville along Cinder road were swaths of trees were downed with convergent signatures and multiple structures were damaged 5) About 3-3.5 miles south of Strasburg from near Weaver road to White Oak road where convergent patterns of trees downed with structure damage and a collapsed barn 6) About 2 miles southeast of Strasburg near Reservoir Road were a convergent pattern of snapped tree trunks were evident.
The storm produced 15 injuries, all in the city of Paradise where a open-air horse pavilion collapsed at Paradise Park. Along the path, approximately 50 structures were damaged, and several barns destroyed. An estimated 2000 to 3000 trees were knocked down, along with 2 small high tension towers in the Buck area. Initial estimates from County Emergency Management put damage in the 5 to 7 million dollar range.