Vulnerable Northeast SLOSH Scenarios

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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Hurricane Earl: Storm Chase Recap!

September 2–3, 2010 – Chatham, Massachusetts, Cape Cod

Well, I am back from chasing Hurricane Earl in Chatham, Massachusetts on the far southeast tip of Cape Cod. Despite Earl's weakened state, having made its closest approach as a strong tropical storm, the experience was unforgettable!

I began tracking Earl the moment it emerged from the west coast of Africa into the Atlantic Ocean as a well-defined tropical wave which became Tropical Depression #7 on August 25, and later that day became Tropical Storm Earl. Fighting shear and the outflow from major Hurricane Danielle, Earl was slow to get its act together, but as it approached the northern Leeward Islands on August 29, it was game on!

Earl became a monster category 4 hurricane on August 30 and fluctuated in intensity while remaining a major hurricane as it moved northwestward towards the mid-Atlantic coast of the United States. Earl weakened to a category 2 hurricane as it neared the North Carolina coast and further weakened to a strong tropical storm as it neared Cape Cod and surrounding islands.

Earl's forecast sure was tricky, but ya know... I have give it up for the computer models! They handled this storm extremely well, maintaining convergence for days on a "just offshore" scenario. Many folks speculated that Earl could or would make landfall on the North Carolina coast or Cape Cod (or even Long Island), but the evidence available showed otherwise. I am not a professional forecaster, but I do have common sense to believe scientific evidence, and it is that evidence that eventually made this forecast pan out as expected.

I want to 'shout out' to my good friend Greg Nordstrom who called the scenario that panned out well in advance of it doing so. Greg maintained the offshore path in his forecasts for a good week prior to it taking place and he even nailed the mileage the center of circulation would track in it's closest approach to the U.S. coastline. I also need to shout out to Greg in thanking him for staying in touch with me while on my chase, providing constant updates on Earl's current location and intensity at the time. His input helped put me in the closest position on the Cape to witness the 'worst' (or 'best') of the storm in a mindful, safe manner.

That said, here's a video and some photos that I captured during the chase...





I hope you all enjoyed this recap and footage. Before I conclude I'd like to highlight a couple of my 'personal highs' of the chase...

While on the beach in Chatham I stumbled upon (okay, I admit there was a bit of stalking involved) The Weather's Channel's Paul Goodloe who was kind enough to speak with me for a bit and even took took the time to suggest some great places to ride out the storm. His advice was great and as you saw above – we captured some great shots!

I was also granted a surprise interview with CBS News' Randall Pinkston who was was being followed by a cameraman filming their own coverage of the storm. Randall nicely asked what I was doing there, riding out the storm!? I explained I was chasing Earl and within seconds I had a camera on me and a microphone pointed towards my face... and the result – this interview!


Well there you have it! I look forward to bringing you even more from a bigger, stronger storm in weeks to come!

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