Possibility is not so little, as it's happened before.
From http://www.ccsr.columbia.edu/information/hurricanes/
Hurricanes, Sea Level Rise, and New York City
With a population of over 8 million people, many billions of dollars in property at stake, and hundreds of miles of shoreline, New York City is particularly vulnerable to the threat of severe hurricanes. In spite of its mid-latitude location (~41°N), New York City and the surrounding region have experienced numerous hurricanes, some of which have produced serious damage and loss of life. Future rising sea levels associated with global warming are another cause for concern. Not only would the city be threatened by higher floods associated with hurricanes and other coastal storms, but the interval between floods of a given elevation could drop sharply.
Major Hurricanes of the Past
The only hurricane whose eye hit what is now New York City directly occurred on September 3, 1821, making landfall at Jamaica Bay. Moving northward rapidly, the storm (rated a Category 4 on the Saffir-Simpson scale) produced a storm surge of 13 feet in only one hour, causing widespread flooding of lower Manhattan as far north as Canal Street. However, the storm caused few deaths because the population density was rather low at the time.
Figure 1: Storm surge from the 1938 hurricane at the Battery, New York City (Source: NWS Historic Collection).
In late August, 1893, a powerful hurricane (estimated as a strong Category 1) wiped out Hog Island, a small resort island off Rockaway Beach. The 'Long Island Express' or 'Great Hurricane of 1938' (Category 3) slammed across central Long Island and ripped into southern New England on September 21, 1938, killing nearly 700 people and injuring thousands more (Figure 1). The storm, striking with little advance warning (this in the days long before weather satellites), raised a wall of water 25 to 35 feet high, sweeping away protective barrier dunes and buildings. Because of the tremendous population growth and development that have occurred since then, damages from such a storm today would be enormous.
On September 12, 1960, Hurricane Donna (Category 3) pounded New York City with winds gusting up to 90 miles per hour, dumped five inches of rain, and flooded lower Manhattan almost to waist level on West and Cortlandt Streets (at the southwest corner of what later became the site of the World Trade Center). The water level at the Battery tide gauge (in lower Manhattan) registered 8.4 feet above mean sea level. Normal travel was disrupted as airports sharply curtailed service, subways shut down, and highways closed due to flooding.
On December 11, 1992, a winter storm pummeled New York City with hurricane-force wind gusts of up to 90 miles per hour, causing tidewaters to rise 7.7 feet above normal. The nor'easter crippled transportation, business, and schools, produced numerous power failures, and flooded wide areas.
The New York metropolitan transportation system is particularly vulnerable to disruption by major storms even at present, since most area rail and tunnel points of entry as well as the three major airports lie at elevations of 10 feet or less. This elevation represents a critical threshold. Flood levels of only 1 to 2 feet above those of Hurricane Donna or the December 1992 nor'easter could have resulted in massive inundation and even loss of life.
Figure 2: Hurricane Floyd sweeping across the mid-Atlantic states, Sept. 14-18, 1999, causing widespread flooding and damage. (Source: NOAA/National Climate Data Center)
Hurricane Floyd (Category 2) was the most recent hurricane to hit New York City (Figure 2). With sustained winds of 60 mph, Floyd dumped 10-15 inches on upstate New Jersey and New York over a 24-hour period in September 1999, causing extensive inland flooding. However, because the hurricane struck at low tide and was already beginning to dissipate as it made landfall on the Long Island shoreline, it did not produce a significant storm surge.
New York City at Risk
Because of the unique configuration of the shoreline, New York City is especially vulnerable to major hurricanes that travel northward along a track slightly to the west of the city. Since the highest, hence most destructive, winds lie to the right of the eye of a hurricane, a storm moving on such a path would pass directly over the city. Furthermore, the counterclockwise, westerly flowing winds of the approaching hurricane funnel surge waters toward the near right-angle bend between the New Jersey and Long Island coasts into the apex, i.e., the New York City harbor.
Surge levels for hurricanes of Categories 1-4 have been calculated by the U.S. Army Corps of Engineers for the 1995 Metro New York Hurricane Transportation Study using NOAA's SLOSH model. A Category 3 hurricane on a worst-case track could create a surge of up to 25 feet at JFK Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery, and 16 feet at La Guardia Airport. These figures do not include the effects of tides nor the additional heights of waves on top of the surge. Surge levels for a Category 4 hurricane would be even higher, reaching 31 feet at JFK Airport and Lincoln Tunnel, 29 feet at the Battery, and 21 feet at La Guardia. Although a Category 4 hurricane at the latitude of New York City is extremely improbable at present due to the relatively cold water offshore, some studies suggest that hurricane strengths will intensify as oceans become warmer. Therefore, in the future, a Category 4 hurricane, while still remaining a very rare event, might potentially survive into these latitudes. With several feet of sea level rise, the results could be catastrophic.
A Taste of Things to Come?
How would continuing sea level rise related to global warming affect New York City? A 2001 study by Columbia University scientists for the U.S. Global Change Research Program examined a number of impacts of climate change on the New York City metropolitan area, including sea level rise. Regional sea level trends of the past century range between 0.08 to 0.16 in/yr (2 to 4 mm/yr). From a suite of sea level rise scenarios based on an extrapolation of historical trends and outputs from several global climate model simulations, the researchers projected a rise in sea level of 11.8 to 37.5 inches (30 to 95.5 cm) in New York City and 9.5 to 42.5 inches (24 to 108 cm) in the metropolitan region by the 2080s. Flooding by major storms would inundate many low-lying neighborhoods and shut down the metropolitan transportation system with much greater frequency. The 2001 study suggested that by the 2080s the flood levels of today's 100-year storm (including both hurricanes and powerful nor'easters) would be more likely to recur, on average, as often as once in 60 to once in every 4 years.
From a report that was referenced in a presentation I attended:
According to the 1995 Metro New York Hurricane Transportation Study, a category three hurricane on a worst-case track could create a surge of up to 25 feet at JFK Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery, and 16 feet at La Guardia Airport. These figures do not include the effects of tides or the additional heights of waves on top of the surge.
From http://www2.sunysuffolk.edu/mandias/38hu...uture.html
According to the United States Landfalling Hurricane Probability Project:
* 23% probability that NY City/Long Island will be hit with a tropical storm or hurricane in 2008. Normal value is 15%.
* 14% probability that NY City/Long Island will be hit with a hurricane in 2008. Normal value is 9%.
* 7% probability that NY City/Long Island will be hit with a major hurricane (category 3 or more) in 2008. Normal value is 4%.
* >99.9% probability that NY City/Long Island will be hit with a tropical storm or hurricane in the next 50 years.
* 99.4% probability that NY City/Long Island will be hit with a hurricane in the next 50 years.
* 90% probability that NY City/Long Island will be hit with a major hurricane (category 3 or more) in the next 50 years.
