News•October 30, 2012

Hurricane Sandy Paralyzes New York, New Jersey

For years, public officials and coastal residents of the Mid-Atlantic and Northeast were told that the region is extraordinarily vulnerable to storm surge from nor’easters and hurricanes, but it took Hurricane Sandy, an unprecedented combination of both of those storms, to realize the worst-case scenario on Monday evening. When the storm roared ashore near Atlantic City at 8 p.m. on Monday, it pushed a record high wall of water into Lower Manhattan and coastal New Jersey, flooding parts of Lower Manhattan, including many subway tunnels, splintering the famed boardwalk in Atlantic City, and washing away homes from coastal Rhode Island down to the southern tip of New Jersey.

Water pours into the Hoboken PATH station, viewed via a Port Authority surveillance camera and broadcast via social media networks on Monday night.
Credit: kenobryan/Instagram.

Hurricane Sandy killed at least 33 people in the U.S., knocked out power to more than 7.2 million people — 2.4 million of them in New Jersey alone. It also dumped up to a foot of rain in some places, and buried the higher elevations of West Virginia under 2-to-3 feet of snow. The storm has been unparalleled in meteorological history for its immense geographical scope, the multitude of hazards it unleashed, and the record storm surge it caused. It is almost certain that this storm will wind up being one of the top 10 costliest hurricanes on record, and it comes soon after Munich Re, a global insurance giant, warned of increasing natural disaster losses in the U.S., a trend the company said is related to global climate change.

At a Tuesday morning news conference, a weary New Jersey Governor Chris Christie said the damage done to his state is “unthinkable.”

“It is beyond anything I ever thought possible,” Christie said, noting that railroad freight cars were tossed onto the New Jersey Turnpike, homes were swept away from their foundations and onto a major coastal road, and rail stations in Hoboken, Secaucus, and Newark were flooded.

In New York City, the storm was the most devastating event to happen since the terrorist attacks of Sept. 11, 2001.

The storm surge at The Battery in Lower Manhattan was the highest ever recorded, and it surpassed even the most pessimistic forecasts, with the maximum water level reaching 13.88 feet above the average of the daily lowest low tide of the month, known as Mean Lower Low Water, including a storm surge component of 9.23 feet. That broke the official record of 10.5 feet above Mean Lower Low Water set in 1960 during Hurricane Donna, as well as a record set during a hurricane in 1821.

Or to put this another way, the water level at The Battery rose to 9.15 feet above the average high-tide line.

Facebook user Dann Cuellar posted this image of floodwaters inundating Atlantic City, N.J. on Oct. 29.
Click to enlarge the image.
Credit: Dann Cuellar.

Sandy's record-setting tidal flooding came in at the top end of storm surge forecasts, which were between 6-11 feet in Lower Manhattan.

The Wall Street Journal’s Eric Holthaus said that since 1851, only a foot and a half separated the previous top 10 coastal floods in New York City, which includes some of the biggest storms to ever hit the region (Hurricanes Donna and Irene, 1991’s the Perfect Storm, and several major nor’easters). “Sandy's new coastal flood record for New York City is more than 3 feet above the previous record — more than double the range between the previous top 10,” he wrote.

Part of the reason the flooding was so significant was that the maximum surge occurred right around the time of high tide.

The high water poured into Lower Manhattan from the harbor and the swollen Hudson and East Rivers, with reports of extensive flooding in Battery Park City, the East Village, near Ground Zero, in parts of Brooklyn such as Coney Island, Dumbo, and Red Hook, and Staten Island. Numerous water rescues took place on Monday night, including some at police and fire stations that were located in low-lying areas.

Transit officials are just assessing the damage done when corrosive seawater poured into the subway system, one of the city’s biggest fears. Mayor Bloomberg said that it could be several days before service is fully restored.

Officials had shut down entire subway system ahead of the storm, which may have helped to minimize lasting damage to electrical equipment. In total, the storm surge, which came on top of the unusually high tide triggered by a full moon, flooded seven subway tunnels under the East River, according to a statement from MTA chief Joseph A. Lhota.

“The New York City subway system is 108 years old, but it has never faced a disaster as devastating as what we experienced last night. Hurricane Sandy wreaked havoc on our entire transportation system, in every borough and county of the region. It has brought down trees, ripped out power and inundated tunnels, rail yards and bus depots,” Lhota said. “In 108 years, our employees have never faced a challenge like the one that confronts us now. All of us at the MTA are committed to restoring the system as quickly as we can to help bring New York back to normal.”

The New York Port Authority is also assessing flood damage at the area’s major airports. At LaGuardia Airport in Queens, the East River overtopped a sea wall and flooded at least parts of the runways, and there were some unconfirmed reports on Monday night that it reached the terminal areas as well, and flooding was also observed at JFK Airport. New York area airports remain closed on Tuesday due to the flooding, since seawater may have damaged runway lights and navigation aids that help aircraft land safely.

Sandy Hook, N.J., also saw a record storm surge. The gauge stopped reading there at 8.1 feet above the average high tide level, while the water was still rising. Hurricane Donna in 1960 only reached 5.2 feet above the average high tide. Sandy also generated the third-highest storm surge on record at Philadelphia.

The storm, which technically made landfall as a post-tropical cyclone since it was losing the structure of a purely tropical weather system, according to the National Hurricane Center, also brought high winds, heavy rain, and heavy snows to the eastern third of the country.

A wind gust of 78 mph was recorded at Newark Airport, 79 mph at JFK, and 96 mph in Eatons Neck, N.Y. Gusts to hurricane force (74 mph or greater) were also recorded from North Carolina to Massachusetts as the storm’s massive circulation—measuring nearly a thousand miles in diameter—moved inland. At the time of landfall, the storm had a minimum central pressure of 946 mb, which tied the record for the lowest air pressure reading for any storm to hit the northeastern U.S. An air pressure reading that low is an indication of the storm’s ferocity; the only other northeastern storm that compares was the 1938 hurricane, which killed hundreds of people.

Can This Be Blamed on Climate Change?

While hurricanes are no stranger to the East Coast, they don’t normally strike so far north this late in the season, since water temperatures are typically too cool to sustain them. However, this year, water temperatures off the East Coast were unusually warm. Michael E. Mann, a climate scientist at Penn State University, said that about 1 degree of the several degree water temperature anomaly can be attributed to manmade climate change.

In addition to the warmer than average ocean temperatures, the storm also was energized by a powerful jet stream that drove a strong push of Arctic air southeastward from Canada and into the Midwest and Southeast. This jet stream, and the clash of warm and cold air masses, injected the storm with an added dose of energy right before landfall, and helped it transition from a hurricane into a larger nor’easter that was just as strong.

At the same time, the upper air flow over the Atlantic Ocean was jammed by a powerful area of high pressure near Greenland and a storm system in the Central Atlantic, leaving the storm no escape route away from the U.S.

Satellite image of Hurricane Sandy as it strengthened over the warm ocean waters off the East Coast.
Click to enlarge the image.
Credit: NASA/NOAA.

The overall upper air weather pattern that steered Sandy Sandy, and helped it transition into a hybrid storm, is relatively unusual, but not unheard of. The problem is that the pattern is occurred at precisely the wrong time—when a hurricane was moving out of the Caribbean.

Weather Channel hurricane expert Bryan Norcross wrote about this on Oct. 26. “The freak part is that a hurricane happens to be in the right place in the world to get sucked into this doubled-back channel of air and pulled inland from the coast,” he said. “And the double-freak part is that the upper-level wind, instead of weakening the storm and simply absorbing the moisture — which would be annoying enough — is merging with the tropical system to create a monstrous hybrid vortex. A combination of a hurricane and a nor’easter.”

Recent studies have shown that strong blocking patterns such as the one that is currently over the Atlantic have appeared with greater frequency and intensity in recent years. Some scientists think that may be related to the loss of Arctic sea ice, which is one of the most visible consequences of manmade global warming. The 2012 sea ice melt season, which ended just one month ago, was extreme, with sea ice extent, volume, and other measures all hitting record lows. The loss of sea ice opens large expanses of open water, which then absorbs more of the incoming solar radiation and adds heat and moisture to the atmosphere, thereby helping to alter weather patterns. Exactly how weather patterns are changing as a result, however, is a subject of active research.

Global warming is also expected to alter hurricane frequency and strength, making North Atlantic hurricanes slightly more powerful, while reducing the overall number of storms during coming decades. Detecting such changes in the observational record is difficult, considering the varying ways people have kept tabs on hurricanes prior to the era of hurricane hunter aircraft flights. A recent study published in the Proceedings of the National Academy of Sciences found that warmer sea surface temperatures are tied to an increase in stronger Atlantic hurricanes.

Regardless of any changes in hurricane intensity, storms are already likely to produce more signiifcant coastal flooding, since sea levels have been rising during the past century, due to a combination of warming ocean waters and melting of polar ice caps. If Hurricane Sandy were to strike New York City in 2050, it would cause even more damage, since sea levels are expected to be considerably higher by midcentury. In fact, a recent study found that sea level rise has taken place at an accelerated rate at locations north of Norfolk, Va., and if this pace continues the Northeast could see much higher sea levels than other parts of the East Coast by midcentury.

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