Sandy's Analysis

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By Stephen Gode on November 1, 2012, 5:37pm Last modified: November 2, 2012, 10:50pm

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(In the image above, rapidly falling pressure on the order of over 10 millibars in 3 hours indicated the approach of Sandy just before landfall near Atlantic City, New Jersey. Courtesy of College of Dupage)

Hurricane Sandy had one of the most unusual tracks for any tropical system. Sandy track was a bit similar to the 1938 New England Hurricane and the 1903 New Jersey Hurricane, but they did not originate in the Caribbean, for one. They are similar that they became influenced by a trough, and instead of going out to sea; they turned more toward the coast. There have been other storms in the past that transitioned from a hurricane or tropical system into a snowstorm. One example was the New England’s Snow Hurricane of 1804, but instead of heavy snow in New England, the heavy snow was mainly in the higher elevations of West Virginia. Sandy became influenced by multiple other systems, but generally slithered North from the Caribbean and revved back like an upper-cut punch into the East Coast of US.

There was a negative NAO to indicate potential for a storm along the coast a week in advance. Also, some models were also indicating a tropical system or a nor’easter over a week in advance. One of the models, ECMWF, handled Sandy fairly well more than a week out by generally following the actual track of Sandy. With days before the storm was supposed to make landfall, it was hard to imagine the track and intensity to be believable on the models, because it was so rare. The MJO was in favor for the Atlantic to have enhanced tropical development before Sandy even organized into a Tropical Storm from the start. The Arctic Oscillation was negative; which sometimes indicate coastal storm development, too. The PDO and PNA was negative; which is not typically favorable for a storm along the East Coast when predicted to make landfall in the Mid-Atlantic.  

The storm was starting to really be a hybrid when it was just coming out of the Bahamas when additional shear and cooler and drier air starting influencing the system.  The wind field started expanding when Sandy was going past the Bahamas. She weakened to a Tropical Storm briefly, but then additional strengthening occurred. She became really influenced by the trough and was becoming pushed out to sea. Although, Sandy was interacting by a Fujiwara Effect (not completely the same, because usually from multiple tropical systems interacting) from a large ocean storm to the east and then the digging negatively-tilted trough to the west (which influenced Sandy the most). After, the trough had an additional vorticity maximum flying over across America which dug around the trough, which then became negatively tilted. The energy cut-off from the flow of the jet stream and the proximity to Sandy pulled Sandy back to the coast to phase energy for additional strengthening. A baroclinic event started to take place with Sandy approaching the coast. Cold dry air and warm moist air along with well above normal sea surface water temperatures of the Gulf Stream that made Sandy strengthen like a nor'easter  Sandy became more Post-Tropical at landfall, because it became more of a vertically stacked low pressure center along with friction of the coast to start to weaken her. There was a blocking high to the Northeast to keep the system from continuing Northeast out to sea. Sandy became cold core when snow was falling near Sandy’s center when she was centered over Pennsylvania.

One of Sandy’s most devastating impacts was the storm surge/coastal flooding. Since, the storm expanded into such a monstrous system affecting areas up to 1000 miles wide for tropical storm force wind. A large part of the western Atlantic Ocean was influenced by wind stress from Sandy to increase the potential for high storm surge, which occurred. Also, coastal features, high astronomical tides, and a tightening pressure gradient allowed for high storm surge. The persistent easterly wind along the coast North of Sandy created a funneling effect in the Long Island Sound, bays, east facing beaches, and river inlets. From the Carolinas to Southern New England, the coast is generally concave inward to allow for additional accumulation of coastal flooding when Sandy was making landfall. Storm surge was up to 8 to just over 13 feet high in Long Island Sound and areas further south down the coast north of Sandy's landfall. Also, the coastal flooding occurred during at least three high tides from the long duration of the storm during a full moon.

This was a historic and 'once in a lifetime' type of storm for our area. Although, with all the crazy weather we have been having in our area the past couple of years, maybe the possibilities are endless. Global warming has the potential to create more violent storms, so this is a by-product of it, in a way. There will always be normal variations of cold and warm periods in the weather of the world, but it is tough to predict what these extreme events setup for the long-range outlook. Some indicate we are going into a long term cooling pattern in years to come or soon, which very well maybe, but the strong evidence of CO2 increase with global warming is undeniable.

Tragically, this storm took more than 80 lives from reports.  The early estimated cost of Sandy’s impacts maybe 50 or more billion dollars from some reports. The cost of Sandy is a huge hit to the already hurting economy. Reports, estimate over 4.5 million power outages occurred from the storm. Hopefully, a storm of this magnitude will not happen again or at least in the near future. With hope, this storm will create tremendous rebuilding and growth to increase the economy for generations to come like the 1938 hurricane did for Long Island.

 

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Stephen Gode

Town: North Haven, CT  

Reporting for WXedge since September 2012.

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