5 reasons why Sandy is expected to be a superstorm
1 Northern extratropical storm. Sandy is expected to become what's known as an extratropical storm. Unlike a tropical system like a hurricane, which gets its power from warm ocean waters, extratropical systems are driven by temperature contrasts in the atmosphere.
2 Early winter storm. Sandy is expected to merge with a wintry system from the west, at which point it will become the powerful superstorm.
3 Arctic air from the north. Frigid air coming south from Canada also is expected to collide with Sandy and the wintry storm from the west, creating a megastorm that is expected to park over the Northeast for days.
4 High tides. Further complicating matters is the possibility for dangerous storm surges up to 8 feet from Maryland to Rhode Island.
5 Combo of snow and wind. This increases the risk for widespread power outages. Storms in recent years have left hundreds of thousands of people in the eastern U.S. without power, sometimes for days at a time.