Officials: Lancaster County tornado unprecedented

Wednesday was a day like no other in Pennsylvania weather history.

The powerful tornado that destroyed an Amish school near the Lancaster-Berks Counties border was unprecedented for February in the period of record, the government's Storm Prediction Center said Thursday.

The twister, spun from the potent front that set off strong thunderstorms and flooding downpours in the Philadelphia region, was an EF2 on the Enhanced Fujita Scale, packing winds of 120 to 125 mph, the National Weather Service said.

It was the first tornado of that strength observed in the state in February in records dating to 1950, said Greg Carbin, warning-coordination meteorologist for the storm center in Norman, Okla.

It touched down in the dark, at 7:38 p.m., cutting a path 400 yards wide and traveling 4.7 miles through a sparsely populated area around White Horse, Lancaster County.

A second tornado, an EF1 with 100 mph winds, hit Wyalusing, northwest of Scranton in Bradford County, thus setting another precedent.

Before Thursday, Carbin said, only one February tornado had been verified in the state: what would have been an EF1 on Feb. 16, 1990, in Bucks County.

No injures were reported in either of Wednesday's tornadoes, but in addition to leveling a school, the EF2 collapsed barns and damaged 40 houses, according to reports.

Thunderstorms spawned by the front resulted in several thousand power outages in the Philadelphia region and set off flooding along the Schuylkill in Montgomery County and the Brandywine Creek at Chadds Ford.

A gust of 63 mph was reported in Elverson, Chester County, and the storm knocked down trees and power lines. At Philadelphia International Airport, several dozen flights were delayed or canceled. SEPTA and PATCO reported weather-related delays.

A tornado watch had been posted for the region Wednesday night but no tornado was sighted.

Tornadoes are scarce in this area in February because "the warm moist air needed to fuel moist updrafts is so far removed from that part of the country," Carbin said.

Those conditions were present Wednesday, however, as winds from the south ahead of a storm tracking west of the Ohio Valley mined a rich moisture supply from the Gulf of Mexico, further juiced by above-normal gulf water temperatures, he said.

twood@phillynews.com610-313-8210 @woodt15