Monday, October 29, 2012

Storm surge potential for Hurricane Sandy likely to flood NYC subway system

In Landstrike, my fictional version of a major hurricane striking New York City, one of the more devastating effects of the storm was flooding of the NYC subway system due to storm surge up the Hudson River.

Fictional hurricane Nicole in Landstrike was predicated on a worst case scenario for New York--a strong hurricane striking just south of the city, thereby forcing the greatest storm surge up the Hudson River.

It now appears that Hurricane Sandy may bring that disastrous scenario to real life.  Here's what meteoroligist Jeff Masters had to say earlier today about the storm surge potential:

"This evening, as the core of Sandy moves ashore, the storm will carry with it a gigantic bulge of water that will raise waters levels to the highest storm tides ever seen in over a century of record keeping, along much of the coastline of New Jersey and New York. The peak danger will be between 7 pm - 10 pm, when storm surge rides in on top of the high tide. The full moon is today, which means astronomical high tide will be about 5% higher than the average high tide for the month, adding another 2 - 3" to water levels. This morning's 9:30 am EDT H*Wind analysis from NOAA's Hurricane Research Division put the destructive potential of Sandy's winds at a modest 2.9 on a scale of 0 to 6. However, the destructive potential of the storm surge was record high: 5.8 on a scale of 0 to 6. This is a higher destructive potential than any hurricane observed since 1969, including Category 5 storms like Katrina, Rita, Wilma, Camille, and Andrew. The previous highest destructive potential for storm surge was 5.6 on a scale of 0 to 6, set during Hurricane Isabel of 2003. Sandy's 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' and a storm tide of 9.5' above MLLW 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. According to the latest storm surge forecast for NYC from NHC, Sandy's storm surge is expected to be 10 - 12' above MLLW. Since a storm tide of 10.5' is needed to flood the subway system, it appears likely that portions of the NYC subway system will flood. The record highest storm tide at The Battery was 10.5', set on September 15, 1960, during Hurricane Donna."

We suspect that subway flooding is only part of the story, as there are many low lying areas of NYC and its surrounding communities along the Hudson River.  We don't think it will be quite the magnitude of Landstrike, which was a more powerful and concentrated storm than Sandy, but we do think the coming disaster will cost billions and have long-lingering effects.

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