BLOOMSBURG — Emergency management authorities urged Pennsylvanians on Friday to prepare for a potentially dangerous super storm that could pound the state with damaging winds, several inches of rain and maybe snow, possibly leading to widespread power outages.

As Gov. Tom Corbett declared a disaster emergency, residents were told to stock their homes with enough batteries, water and food for three days in light of the monstrous, slow-moving mayhem predicted to strike the mid-Atlantic early next week.

The brewing weather system involving Hurricane Sandy is expected to pummel the East Coast harder than Hurricane Irene, which last year left hundreds of thousands of Pennsylvanians without power and eventually led to historic flooding.

In Philadelphia, the mayor told residents of flood-prone neighborhoods to make plans to stay with family or friends and to be packed and ready to leave by Sunday afternoon. Rain is predicted to begin falling in the city Sunday evening, he said, with the heaviest downpours starting Monday night.

“Do not wait until Monday to try to figure out what to do,” Mayor Michael Nutter warned.

Sandy is expected to merge with a wintry front to create a mess that some have dubbed “Frankenstorm.” The entire Eastern region will be hit with steady, strong and damaging winds and rain for several days, according to federal forecasters. Western Pennsylvania could get snow.