Not Just A Hurricane: What Made Sandy A Superstorm

NEW JERSEY — In the days before Superstorm Sandy made landfall in New Jersey, there was considerable discussion among local residents of "should we stay or should we go?"

The storm was straddling the line between tropical storm and Category 1 hurricane, packing some hurricane-force winds as it made its way north from the Caribbean. It didn't appear to the untrained eye that it was going to be much of a problem.

"I knew the house wasn't going to blow apart," Sandy survivor Charlie Lord said back in 2012, after he and his wife spent six days stuck in Lavallette when he decided they could ride out the storm, thinking it was going to be no big deal.

New Jersey had seen hurricanes and vicious nor'easters before. There was the Ash Wednesday storm of 1962, which inundated the coast during a 72-hour cycle of five high tides. There was the December 1992 nor'easter that pummeled the coast, buried roads and vehicles in sand up to the windows in Point Pleasant and leaving Long Beach Island under water.

Hurricane Gloria dealt New Jersey a glancing blow, and Hurricane Irene, just a year before Sandy in 2011, caused most of its damage inland.

Sandy, however, packed a punch not seen often in the history of hurricanes, because it wasn't simply a hurricane: It was what climatologists call "an extratropical storm," because it has both the characteristics of a tropical storm and winter storm.

"This was a hybrid storm," said David Robinson, New Jersey's state climatologist and a professor at Rutgers University, which is home to the Rutgers Climate Institute.

"It was a hurricane wrapped in a nor'easter," Robinson said, a combination that led to the storm being more than 1,000 miles across, stretching out to Chicago, north to Greenland and well south down the East Coast.

It was similar to the Halloween 1991 storm that later was dubbed "The Perfect Storm" — the one highlighted by the movie that focused on the disappearance of the commercial fishing boat the Andrea Gail.

Tropical systems typically lose strength as they move north because they pull cooler water from the depths of the ocean — "which cuts the legs out from under them," Robinson said. But in the case of Sandy and of the "Perfect Storm," the tropical storm strengthened as it crossed into the middle latitudes of the ocean, because the water below the surface was still warm.

As Sandy moved from the tropical to the middle latitudes, it also transitioned toward the characteristics of a winter storm, which draws its energy from the atmosphere instead of the ocean temperature, and that caused the storm to spread out so far. A video from the National Oceanic and Atmospheric Administration shows satellite imagery and an animation of how Sandy became a superstorm.

The left turn toward land was the result of a "blocking high," a "major deviation of the high-altitude jet stream,"according to a report by Malcolm Bowman of the SUNY-Stony Brook Sea Grant program. That high-pressure system parked north of the storm and prevented it from turning out to the eastern Atlantic.

All of the power of the storm bore down on the East Coast, with New Jersey bearing the brunt.

Robinson said the transformation from tropical cyclone to extratropical storm, which he said Sandy was in the midst of when it made landfall, is why the effects were so intense and in many ways not like a hurricane.

While there was some wind damage at the coast, it was the power of the wind and the speed at which Sandy was moving — 28 mph at the time of landfall, according to the National Weather Service — that were driving the water toward the coast over the vast distance that contributed to an unprecedented level of flooding compared with what is typically associated with a hurricane.

"The winds were not hurricane-force," Robinson said. It was the fetch — "the distance the wind was blowing over the water, because Sandy was so large, that drove the storm surge."

The result, Robinson said, was Sandy "pushed far more water onto the coast than a smaller nor'easter with those kinds of winds."

That extra power contributed to the breaches in Mantoloking, and the power of the surge combined with minimal dunes led to the extensive damage along much of the northern Ocean County barrier island, including Ortley Beach and Seaside Heights.

The surge, which came at high tide, also caused the flooding seen in the Meadowlands area, in lower Manhattan, along Long Island Sound and in Connecticut, Robinson said.

The winter storm characteristics and the unusual direction of the storm was why areas in South Jersey saw flooding rains of 8 to 12 inches, and farther inland dealt with blizzard conditions.

The vast area of wind coverage and the direction of the storm was why the back bay marshes flooded so significantly, Robinson said. "The orientation of that storm was so unusual it brought the storm into interior bays."

A month after Sandy, a report presented to Ocean County officials showed just how extensive the surge was, prompting Freeholder Joseph Vicari to call it "a 500-year event." Read more: Freeholders See Maps Of Sandy's Surge: 'This Was A 500-Year Event'

With sea levels rising, Robinson said future storms, including ones that resemble Sandy, will continue to do increased damage simply because they're starting from a higher water level, and because we continue to rebuild at the shore.

"We don’t know when we’re going to have another storm like Sandy," he said, "but in 30 years we won't need a Sandy to bring that level of flooding … it’s going to get progressively worse."

There have been worse storms — "there was an 1820 hurricane hit much harder, it clobbered Cape May," Robinson said, that was probably a Category 2. But the damage from that storm wasn't as extensive simply because of the difference in the population living along the coast at that time compared with 2012.

While comparisons have been made recently between Sandy and Hurricane Ian, which caused heavy damage in Fort Myers Beach and Sanibel in Florida, Robinson said the biggest difference between the storms is Ian was much more compact. The destruction in the Fort Myers area is significant, areas just beyond — including the Tampa-St. Petersburg area — didn't incur quite as much damage.

For all of the damage that Sandy did and for the struggles that remain 10 years later, the fact that Sandy happened was necessary, Robinson said.

"The best thing about that storm is it happened. It demonstrated such a storm can happen and we need to prepare," he said.