The early warnings about Hurricane Sandy have included some words that weather forecasters don't use lightly like 'major' or 'potentially-devastating'.  Why is this weather event so potentially dangerous?

Earlier this week many forecast tracks shows Sandy drifting out to sea.  Now nearly all trajectories for this storm place it somewhere along the Northeast Coast.  What worries weather forecasters about Sandy is the potential of a landfalling hurricane along with a deep cold front that will push through the region at about the same time. That's what happened in October of 1991 in a weather event dubbed "The Perfect Storm."

NOAA via Wikipedia

The Perfect Storm began as the harmless Hurricane Grace.  Grace formed during late October of 1991 in the open waters of the Atlantic Ocean.  It made no landfall and did no damage.  The only effect was some windy conditions on Bermuda.  As Grace drifted northward and became extratropical, it was sucked into a low pressure system.  The super-storm then caused high waves and major flooding.

Sandy has shown similar potential, with the added threat of snow that would come from the colder temperatures associated with the front that would absorb Sandy.  The path of the storm, as shown above from the National Weather Service places Sandy as a hurricane into Monday about as a far north as North Carolina.  The storm is projected to lose its tropical characteristics on Tuesday when it skates the coast of New Jersey.  What forecasters are not yet able to say with certainty is if the storm would continue north and make a hit on the New York City metropolitan area or veer east to become a classic "Long Island Express."