NEW YORK — Hundreds of thousands of New Yorkers were told Thursday to pack a bag and prepare to be evacuated as the nation’s biggest city braced for its first hurricane in decades.

Mayor Michael Bloomberg ordered nursing homes and five hospitals in low-lying areas evacuated beginning Friday and said he would order 270,000 other people moved by Saturday if the storm stays on its current path.

Hurricane Irene was on track to make landfall Saturday in North Carolina and then move up the East Coast, reaching the New York area by late Sunday.

Evacuating hundreds of thousands of people would be particularly difficult in New York, where there are about 1.6 million people in Manhattan, many without cars. There are about 6.8 million in the city’s other four boroughs.

Irene rolled toward the Carolinas on Thursday with winds of 115 mph. The storm was expected to weaken after brushing North Carolina’s Outer Banks, but it will still likely be a hurricane when it rumbles toward the Northeast.

Forecasters said passing near Manhattan could lead to a nightmare scenario: shattered glass falling from skyscrapers, flooded subways and seawater coursing through the streets.
In the last 200 years, New York has seen only a few significant hurricanes. In September of 1821, a hurricane raised tides by 13 feet in an hour and flooded all of Manhattan south of Canal Street, the southernmost tip of the city. The area now includes Wall Street and the World Trade Center memorial.

In 1938, a storm dubbed the Long Island Express came ashore about 75 miles east of the city on neighboring Long Island and then hit New England, killing 700 people and leaving 63,000 homeless.

Irene is a large storm, with tropical storm-force winds extending nearly 300 miles from its center. And the storm could hit at a time when high tides reach their highest levels, which could amplify flooding. Some experts predict a storm surge of five feet or more. Lower Manhattan could see streets under a few feet of water.

“In many ways, a Category 2 or stronger storm hitting New York is a lot of people’s nightmare, for a number of reasons,” said Susan Cutter, director of the Hazards and Vulnerability Research Institute at the University of South Carolina.

Even if the winds aren’t strong enough to damage buildings made largely of brick, concrete and steel, a lot of New York’s subway system and power lines are underground. The city’s airports are close to the water, too, and could be inundated, as could densely packed neighborhoods. Hospitals were told to make sure generators were ready.

Poised to brush one of the most densely populated parts of the country, Irene could cause billions or even hundreds of billions of dollars in damage, said Kathleen Tierney, director of the Natural Hazards Center at the University of Colorado.

Printed on Friday, August 26, 2011 as: Hurricane Irene preparing New York City for evacuation.