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Queens Chronicle

Hurricane Sandy: a true perfect storm

Record strength, rare track made Sandy a uniquely powerful system

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Posted: Thursday, November 1, 2012 10:30 am | Updated: 11:52 am, Thu Nov 8, 2012.

Hurricanes are not rare in New York. Dozens have hit the area in the last century, including, most recently, Irene, only 14 months ago.

But Hurricane Sandy was not like most of the others.

The destruction of the boardwalks in Rockaway and on the Jersey Shore, along with the record storm surge in Howard Beach and Lower Manhattan, all hint at a storm unlike any the city has seen in living memory.

Sandy was not Irene, or 1985’s Hurricane Gloria, or Hurricane Belle of 1976 or even the 1938 Long Island Express storm, the strongest ever to strike land north of Cape Hatteras, NC.

Hurricane Sandy now rivals the latter’s record.

What caused Sandy to be a storm of record strength was a perfect confluence of different meteorological factors.

Sandy made landfall near Atlantic City, NJ Monday evening as a Category 1 hurricane with top winds of around 85 mph. However, the barometric pressure upon landfall was measured at 946 millibars, just slightly better than the 941 mb-pressure recorded when the 1938 hurricane hit Long Island — as a Category 3. In fact Sandy’s pressure at landfall was similar to that of Hurricane Hugo, a Category 4 hurricane when it struck Charleston, SC in 1989.

Lower air pressure indicates stormier weather. As a general rule, the lower the barometric pressure, the stronger the storm. Category 1 hurricanes typically have a barometric pressure of around 980 to 1,000 mb, making Sandy oddly powerful for a Category 1 hurricane.

Sandy was also one of the largest hurricanes in size to ever develop in the Atlantic Ocean and the largest to ever make landfall. At one point, the mass of clouds swirling around Sandy stretched from Spartanburg, SC to Quebec City, Canada and as far west as Iowa. Its size was attributed to its combining with a frontal system that stalled over the Mid-Atlantic. The two combined, turning Sandy into a post-tropical storm after landfall, which allowed it to maintain its strength even after it left the ocean. Tropical systems cannot survive unless they are over water.

Perhaps the biggest factor that played in Sandy’s favor was the rare path it took during its life. The storm formed in the Caribbean Sea on October 22, strengthened rapidly and struck Jamaica, Cuba and the Bahamas before emerging over the open Atlantic. It rode the Gulf Stream, a current of warm water that flows along the East Coast up the Atlantic Ocean from Florida to Newfoundland, right up until it made the abrupt left turn toward New Jersey. That allowed the storm to continue strengthening right up until Monday. The turn itself was a rare feat, caused by a high-pressure system over the the Canadian maritime provinces that steered it into the coast.

Because of the location of landfall, New York City bore the brunt of the storm. The north and east side of a hurricane — the upper right hand quadrant — is the location with the most powerful winds and storm surge. The New York area was in that part of the storm, which placed the city directly in the path of the strongest winds and highest storm surge, which clocked in at 13.88 feet at Battery Park, breaking the old record by more than three feet.

One thing Sandy did not bring to the area was much rain. Less than an inch of rain fell on New York City during the storm. The majority of the moisture remained on the south side, bringing over 5 inches of rain to Washington, DC and Baltimore, Md.

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