Hurricane Sandy closed in on the United States on Saturday as coastal communities along the East Coast scrambled to prepare for torrential rains, high winds, major flooding and power outages.
Governors in states in the hurricane's path declared emergencies, announcing mandatory evacuations of vulnerable areas. New York City officials discussed whether to shut the subway system on Sunday in advance of the storm.
On its current projected track, Sandy could make U.S. landfall on Monday night or Tuesday morning anywhere between Maryland and southern New England, forecasters said. Some computer models show a likely landfall between Delaware and the New York/New Jersey area.
The hurricane was headed toward densely populated areas with tens of millions of people. Officials urged residents to stock up on food, water and batteries. Worried residents packed stores, buying generators, candles, food and other supplies in anticipation of power outages. Some local governments announced schools would be closed on Monday and Tuesday.
"They're freaking out," said Joe Dautel, a clerk at a hardware store in Glenside, Penn. "I'm selling people four, five, six packs of batteries -- when I had them."
Sandy also threatened to disrupt air travel in the region.
Rain accumulations of up to 12 inches and heavy snowfall inland are considered likely in some areas. As it merges with an Arctic jet stream, forecasters said Sandy has all the ingredients to transform into a "super storm" unlike anything seen over the eastern United States in decades.
"There's no avoiding a significant storm-surge event over a large area. We just can't pinpoint who's going to get the worst of it," National Hurricane Center Director Rick Knabb said.
The White House said President Barack Obama took part in a call with U.S. Homeland Security Secretary Janet Napolitano and Federal Emergency Management Agency (FEMA) Administrator Craig Fugate to discuss preparations for Sandy.
Coastal flooding posed a major threat, particularly in low-lying areas like New York City, the global financial nerve center, and Alexandria, Va., across the Potomac River from Washington, D.C.
"This is not a coastal threat alone," Fugate told reporters, warning of the potential for flooding in Maryland and Pennsylvania, as well as more than 2 feet of snow in West Virginia and southwest Pennsylvania. "This is going to go well inland," he added.
Delaware Governor Jack Markell ordered a mandatory evacuation of an estimated 50,000 people in coastal communities on Saturday. New Jersey's Cape May County ordered an evacuation of its barrier islands, home to some popular beach resorts, by Sunday afternoon.
In New York, authorities were considering closing down the city's buses, subways, commuter railroads, bridges and tunnels as early as 7 p.m. on Sunday, when the last commuter trains would depart, with the entire system to be closed down by 3 a.m. Monday, officials said.