HARRISBURG, Pa.—Gov. Tom Corbett is asking Pennsylvanians to find a safe place and remain there for the duration of what he says could be a very damaging storm that uproots numerous trees, knocks out power to wide areas and causes flooding.

Corbett said Sunday evening that the storm could be historic in scope, nature and magnitude because of the potential for power outages, flooding and wind damage to the state. He says 4 million Pennsylvanians could be affected.

He says most areas will get three to five inches of rain, and some could see six to 10 inches.

Fort Indiantown Gap in suburban Harrisburg is depot to distribute water and generators to parts of the state that need them. He says he's also worried about Philadelphia-area refineries.