The National Weather Service said Wednesday at least three tornadoes touched down during strong storms that raked across the state the day before, bringing heavy rain and high winds.
Experts said there were tornadoes on Tuesday in Indiana, Bradford and Berks counties. There were no reports of injuries.
Heavy rains from the front inundated parts of western Pennsylvania, sending torrents down the streets of one town and requiring several people to be rescued.
Zelienople officials told drivers to avoid several streets because of severe flooding in the town about 30 miles north of Pittsburgh.
In a housing development in Morgantown, more than a dozen homes suffered significant structural damage from the storm.
The weather system brought high winds that scattered debris, downed trees and took out power lines. A few western Pennsylvania schools closed or started late on Wednesday because of flooding problems or power outages.
There were reports of large hail, and some areas received 3 or 4 inches of rainfall over a short period.
A fresh round of Pennsylvania thunderstorms followed on Wednesday, prompting a rush-hour tornado warning in the Harrisburg area.