Yesterday on Facebook I was admiring some graphics posted by Michael Laca, which using computer generated scenarios, depicted SLOSH (Sea, Lake, and Overland Surge from Hurricanes) inundation "worst-case" storm surge situations for several locations in Florida. Michael, a veteran hurricane chaser with over 25 years experience, runs the website TROPMET.COM, and after seeing these startling graphics my interest was immediately sparked to see what would happen "if" a major hurricane barreled into a northeast location from New Jersey to Cape Cod, including New York City. Michael gladly helped me out and produced the SLOSH inundation maps below using the MOM (Maximum Of Maximum) algorithm for each surge basin, which is agnostic of a specific track.
A couple things to note: The SLOSH analysis typically considers hypothetical scenarios – from 10 different directions, four forward speeds, five intensities and 10 to 20 landfall points within a basin, resulting in anywhere from 2,000 to 4,000 combinations of storm scenarios. The program then analyzes each combination and generates a MEOW (Maximum Envelope of Water) for all variations of similar scenarios (such as a category 4, moving northwest at 15 mph, making landfall at 20 different locations within the basin), and then retains the highest surge value at each grid square. The MOM then preserves each of the highest values from each MEOW, resulting in a graphic depicting the highest surge value for any point within the basin across all possible combinations of storms.
So what does that all mean? The maps below show the worst-case scenario at any one point when you consider ALL possible scenarios. That does not mean that for one specific storm scenario, that all areas shown in these maps will experience a "worst-case" surge, since each storm's size, strength, and forward speed will dramatically change the inundation at any particular location. It should also be stressed that these maps are only intended as guidance and should not be used to make decisions on specific evacuations always listen to emergency management and local officials when it comes to an actual event.
Worst case scenario for Manhattan / Hudson River, New York. Exceptionally high surge values of 30–32 feet above MSL (Mean Sea Level) can be expected in several locations, with widespread inundations between 20–25 feet experienced elsewhere.
Worst case scenario for Long Island, New York. Exceptionally high and widespread surge values of 30–33 feet above MSL can be expected along Atlantic facing coastal locations, with extensive inundations between 15–20 feet experienced elsewhere.
Worst case scenario for western Long Island, New York. Exceptionally high and widespread surge values of 30–33 feet above MSL can be expected along Atlantic facing coastal locations, with extensive inundations between 15–20 feet experienced elsewhere.
Worst case scenario for New Jersey / Delaware Bay. Highest surge values of 18–20 feet above MSL can be expected in several locations, with extensive inundations between 10–15 feet experienced elsewhere.
Worst case scenario for Providence, Rhode Island / Cape Cod, Massachusetts. Extremely high surge values of 35–39 feet above MSL can be expected in isolated locations at the heads of rivers and bays, with widespread inundations between 15–20 feet experienced elsewhere.
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