Monday, February 4, 2013

New York's hurricane coast

Sandy brought together a number of variables that all worked together to maximize the damage from a storm that was down to tropical storm wind speeds when it finally made landfall.  One I had not heard of before was the unusual angle which it made landfall.  Essentially taking a left hook into the shore line.

Risks of Hurricane Sandy-like Surge Events Rising
Andrew Freedman, Climate Central, 24 January 2013 (Hat tip: Big Picture)
The impact angle of Hurricane Sandy was its most unusual feature, ensuring the storm surge would case maximum damage, Hall said. The storm's left-hand turn put the most dangerous right-front quadrant on top of New Jersey and southeastern New York, pummeling these areas with an historic storm surge and record high waves. That, combined with astronomical high tides, led to record storm tide levels.The researchers used statistical techniques and computer modeling to simulate millions of “synthetic" tropical cyclones in the Atlantic in order to determine the likelihood of another storm making a Sandy-esque dramatic left hook toward the coast, striking the most heavily populated region of the U.S. at a nearly perpendicular angle.
The study found that Sandy’s track stands alone in the historical record dating back to 1851, and that modeling simulations showed such a track is an event that would occur about once every 714 years. However, that does not mean that a storm like Sandy won’t affect New Jersey and New York for another 714 years, but rather that the average annual probability of another Hurricane Sandy occurring is .14 percent.
That may seem low, but according to Hall and separate research published in Nature Climate Change in February of 2012, global warming-related sea level rise is likely to make destructive storm surges like Hurricane Sandy’s much more common in the next few decades, regardless of whether storms follow a path similar to Sandy.
Anyone who lives in hurricane territory knows they can take odd paths.  As an example, there have been two separate hurricanes named Diane that have made landfall, went back out to see, and then made landfall a second time. 
If I am governor of New York, I am still going to be worried more about inland flooding from high moisture content hurricanes/tropical storms.  But the potential for New York becoming anything like the Hurricane Coast of the Carolinas is really bad news.

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