Landfall: Why New York City Could Get the Worst of Sandy’s Wrath

As the hurricane approaches landfall, scientists say that the areas to the north and east of Sandy's eye will get the worst of coastal flooding and storm surges. And that's bad news for New York City

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Hurricane Sandy is seen moving toward the East Coast of the U.S. in this NASA satellite image taken on Oct. 29, 2012

The famous Will Durant quote refers to earthquakes, but it can work for storms as well: “Civilization exists by geological consent, subject to change without notice.”

As Hurricane Sandy neared landfall on Monday evening, it certainly seemed as if that geological — or meteorological — consent had been withdrawn up and down the Eastern seaboard. Even with the storm still well out to sea, strong winds could be felt from Virginia through New York, and storm surges were already putting low-lying coastal areas under water. And this is just the beginning, with the heaviest surges expected Monday night, as the storm meets a high tide turbocharged by the full moon. New York Governor Andrew Cuomo put it simply during a Monday-morning press conference: “The worst is still to come.”

(MORE: Frankenstorm: Why Hurricane Sandy Will Be Historic)

Understandably, people have been glued to their TV screens — or the website of the National Hurricane Center — trying to track Sandy’s approach as it veers westward from the Atlantic toward shore. It’s easy to assume that wherever the storm makes a direct hit will get the worst of the damage.

But that doesn’t seem to be the case with the supersize Sandy, whose winds will stretch more than 450 miles (720 km) beyond its core. In fact, it appears that the areas directly to the north and east of the storm’s eye could get the worst of the surge and the coastal flooding. And because the storm is projected to make landfall in southern New Jersey, that’s seriously bad news for New York City and its billions of dollars worth of coastal infrastructure.

Why? Sandy has been rolling up the Atlantic Ocean for days, drawing massive amounts of seawater. Hurricane winds move counterclockwise, so the brunt of that destructive force — and the seawater whipped up by the storm — will be felt to the north and east of the eye. (For those south of the storm, the circulation of the hurricane winds will actually push seawater away from the shore — good news for Washington and other Mid-Atlantic areas.) Sandy’s winds are pushing that ocean water north, and like a tsunami, when those surges meet the shallow water along the coast, the waves pile up and spill over, as Pat Fitzpatrick of Mississippi State University told the New York Times:

A storm surge is really caused by one thing. When a storm is approaching land, it starts to encounter shallow water. The water tends to pile up. The shallower the water is, for longer distance, the more vulnerable an area is.

It doesn’t help that New York City is surrounded by shallow water, which puts it at higher risk for potentially record-breaking storm surges on Monday night that could top 11 ft. (3.4 m). That would be disastrous for the people along Long Island and in the low-lying areas of New York City’s five boroughs, which were already seeing flooding early Monday afternoon. But the lasting danger will be to the system of subway and rail tunnels that ties the greater New York region together. A storm surge as high as experts are predicting for Sandy could easily flood tunnels, putting subways and rail out of commission for weeks, if not far longer.

Already, forecasters are estimating that Sandy could cause economic losses as high as $20 billion — greater than the cost of last year’s Hurricane Irene. But if the storm surges rise high enough, the damage is likely to be much greater — probably greater even than the famous 1938 Long Island Express storm, which cost nearly $47 billion in 2012 dollars. (Hat tip to Roger Pielke Jr. of the University of Colorado for the numbers.) Sandy’s wrath will peak Monday night, but chances are the effects will be felt long after.

MORE: Frankenstorm: Why Hurricane Sandy Could Be the Perfect Storm, Part II