Prognostication about Sandy

There are lots of predictions about what impact Sandy could have on the East Coast of the US including the City of New York.  Only time will tell if these prognostications are completely off target or close.  Clearly, we need to anticipate and to some extent prepare for the worst, in order to protect lives and property, but at the same time it is very difficult to predict the final result of these storms even less than 48 hours before they impact.  Even then can the link be made back to climate change…As always it is difficult to make a link about one extreme weather event to climate change…We need to be looking at the longer term trends and people are most certainly doing that.  Here is an excerpt from wunderground (http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2277) on the impact that Sandy could have on the NY subway systems.

Sandy’s storm surge may flood New York City’s subway system, costing billions
Sandy is expected to have tropical storm-force winds that extend out more than 400 miles from the center, which will drive a much larger storm surge than its peak winds would ordinarily suggest. The full moon is on Monday, which means astronomical tides will be about 5% higher than typical, increasing the potential for damaging storm surge flooding. Fortunately, Sandy is now predicted to make a fairly rapid approach to the coast, meaning that the storm surge will not affect the coast for multiple high tide cycles. If Sandy hits near New York City, as the GFS model predicts, the storm surge will be capable of overtopping the flood walls in Manhattan, which are only five feet above mean sea level. On August 28, 2011, Tropical Storm Irene brought a storm surge of 4.13′ to Battery Park on the south side of Manhattan. The waters poured over the flood walls into Lower Manhattan, but came 8 – 12″ shy of being able to flood the New York City subway system. However, the town of Lindenhurst (population 28,000), on the south side of Long Island, was mostly under water due to the storm surge, and fresh water run-off from Irene’s torrential rains, riding on top of a 3 to 4-foot storm surge, allowed the swollen East and Hudson Rivers to overflow at the edges of Manhattan. New York was not as lucky on December 12, 1992, when a 990 mb Nor’easter drove an 8-foot storm surge into Battery Park, flooding the NYC subway and the Port Authority Trans-Hudson Corporation (PATH) train systems in Hoboken New Jersey. FDR Drive in lower Manhattan was flooded with 4 feet of water, which stranded more than 50 cars and required scuba divers to rescue some of the drivers. Mass transit between New Jersey and New York was down for ten days, and the storm did hundreds of millions in damage to the city. The highest water level recorded at the Battery in the past century came in September 1960 during Hurricane Donna, which brought a storm surge of 8.36 feet to the Battery and flooded lower Manhattan to West and Cortland Streets. According to the latest storm surge forecast for NYC from the experimental Extratropical Storm Surge model, run by NOAA”s Meteorological Development Laboratory, Sandy’s storm surge may be higher than Irene’s, and has the potential to flood New York City’s subway system (Figure 4.) The amount of water will depend critically upon whether or not the peak storm surge arrives at high tide or not. If the peak surge arrives near Monday evening’s high tide near 9 pm EDT, a portion of New York City’s subway system could flood, resulting in billions of dollars in damage. I give a 30% chance that Sandy’s storm surge will end up flooding a portion of the New York City subway system.

An excellent September 2012 article in the New York Times titled, “New York Is Lagging as Seas and Risks Rise, Critics Warn” quoted Dr. Klaus H. Jacob, a research scientist at Columbia University’s Earth Institute, on how lucky New York City got with Hurricane Irene. If the storm surge from Irene had been just one foot higher, “subway tunnels would have flooded, segments of the Franklin D. Roosevelt Drive and roads along the Hudson River would have turned into rivers, and sections of the commuter rail system would have been impassable or bereft of power,” he said, and the subway tunnels under the Harlem and East Rivers would have been unusable for nearly a month, or longer, at an economic loss of about $55 billion. Dr. Jacob is an adviser to the city on climate change, and an author of the 2011 state study that laid out the flooding prospects. “We’ve been extremely lucky,” he said. “I’m disappointed that the political process hasn’t recognized that we’re playing Russian roulette.” A substantial portion of New York City’s electrical system is underground in flood-prone areas. Consolidated Edison, the utility that supplies electricity to most of the city, estimates that adaptations like installing submersible switches and moving high-voltage transformers above ground level would cost at least $250 million. Lacking the means, it is making gradual adjustments, with about $24 million spent in flood zones since 2007. At a conference I attended this summer in Hoboken on natural hazards on urban coasts, I talked to an official with Consolidated Edison, who was responsible for turning off Lower Manhattan’s power if a storm surge floods the subway system. He said that he was ready to throw the switch during Irene, but was glad it turned out not to be needed.

 

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