Hurricane Sandy

 

Hurricane Sandy was the deadliest and most destructive tropical cyclone of the 2012 Atlantic hurricane season, as well as the second-costliest hurricane in United States history. Classified as the eighteenth named storm, tenth hurricane and second major hurricane of the year, Sandy was aCategory 3 storm at its peak intensity when it made landfall in Cuba.^[1] While it was a Category 2 storm off the coast of the Northeastern United States, the storm became the largest Atlantic hurricane on record (as measured by diameter, with winds spanning 1,100 miles (1,800 km)).^[2][3]Preliminary estimates assess damage at nearly $75 billion (2012 USD), a total surpassed only by Hurricane Katrina. At least 285 people were killed along the path of the storm in seven countries.^[4] The severe and widespread damage the storm caused in the United States, as well as its unusual merge with a frontal system, resulted in the nicknaming of the hurricane by the media and several organizations of the U.S. government "Superstorm Sandy".^[5][6][7][8]

Sandy developed from a tropical wave in the western Caribbean Sea on October 22, quickly strengthened, and was upgraded to Tropical Storm Sandy six hours later. Sandy moved slowly northward toward the Greater Antilles and gradually intensified. On October 24, Sandy became a hurricane, made landfall near Kingston, Jamaica, a few hours later, re-emerged into the Caribbean Sea and strengthened into a Category 2 hurricane. On October 25, Sandy hit Cuba as a Category 3 hurricane, then weakened to a Category 1 hurricane. Early on October 26, Sandy moved through the Bahamas.^[9] On October 27, Sandy briefly weakened to a tropical storm and then restrengthened to a Category 1 hurricane. Early on October 29, Sandy curved north-northwest and then^[10] moved ashore near Brigantine, New Jersey, just to the northeast of Atlantic City, as a post-tropical cyclone with hurricane-force winds.^[1][11]

In Jamaica, winds left 70% of residents without electricity, blew roofs off buildings, killed one, and caused about $100 million (2012 USD) in damage. In Haiti, Sandy's outer bands brought flooding that killed at least 54, caused food shortages, and left about 200,000 homeless. In the Dominican Republic, two died. In Puerto Rico, one man was swept away by a swollen river. In Cuba, there was extensive coastal flooding and wind damage inland, destroying some 15,000 homes, killing 11, and causing $2 billion (2012 USD) in damage. In The Bahamas, two died amid an estimated $700 million (2012 USD) in damage. In Canada, two were killed in Ontario and an estimated $100 million (2012 CAD) in damage was caused throughout Ontario and Quebec.^[12]

In the United States, Hurricane Sandy affected 24 states, including the entire eastern seaboard from Florida to Maine and west across theAppalachian Mountains to Michigan and Wisconsin, with particularly severe damage in New Jersey and New York. Its storm surge hit New York Cityon October 29, flooding streets, tunnels and subway lines and cutting power in and around the city.^[13][14] Damage in the US is estimated at over $71 billion (2012 USD).^[15][16]

Hurricane Sandy began as a low pressure system which developed sufficient organized convection to be classified as a tropical depression on October 22 south of Kingston, Jamaica.^[17] It moved slowly at first due to a ridge to the north. Low wind shear and warm waters allowed for strengthening,^[17] and the system was named Tropical Storm Sandy late on October 22.^[18] Early on October 24, an eye began developing, and it was moving steadily northward due to an approaching trough.^[19] Later that day, the National Hurricane Center (NHC) upgraded Sandy to hurricane status about 65 mi (105 km) south of Kingston, Jamaica.^[20] At about 1900 UTC that day, Sandy made landfall near Kingston with winds of about 80 mph (130 km/h).^[21] Just offshore Cuba, Sandy rapidly intensified to winds of 115 mph (185 km/h),^[1] and at that intensity it made landfall just west ofSantiago de Cuba at 0525 UTC on October 25.^[22]

After Sandy exited Cuba, the structure became disorganized,^[23] and it turned to the north-northwest over the Bahamas.^[24] By October 27, Sandy was no longer fully tropical, and despite strong shear, it maintained convection due to influence from an approaching trough; the same trough turned the hurricane to the northeast.^[25] After briefly weakening to a tropical storm,^[26] Sandy re-intensified into a hurricane,^[27] and on October 28 an eye began redeveloping.^[28] The storm moved around an upper-level low over the eastern United States and also to the southwest of a ridge over Atlantic Canada, turning it to the northwest.^[29] Sandy briefly re-intensified to Category 2 intensity on the morning of October 29, around which time it had a wind diameter of over 1,150 miles (1,850 km).^[30] The convection diminished while the hurricane accelerated toward the New Jersey coast,^[31] and the hurricane was no longer tropical by 2300 UTC on October 29.^[32] An hour later at about 0000 UTC on October 30, Sandy made landfall near, Brigantine, New Jersey,^[33] with winds of 80 mph (130 km/h).^[34] The remnants weakened over western Pennsylvania, degenerating into a remnant trough on October 31.^[35]

Relation to global warming

See also: Tropical cyclone#Global warming

According to NCAR senior climatologist Kevin E. Trenberth, "The answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be."^[36] Although NOAA meteorologist Martin Hoerling attributes of Sandy to "little more than the coincidental alignment of a tropical storm with an extratropical storm",^[37] Trenberth illustrates by pointing out that steroids in a baseball player's system do not cause home runs all by themselves but do make home runs more likely.^[38] Trenberth does agree that the storm was caused by "natural variability" but adds that it was "enhanced by global warming".^[39] One factor contributing to the storm's strength was abnormally warm sea surface temperatures offshore the East Coast of the United States—more than 3 °C (5 °F) above normal, to which global warming had contributed 0.6 °C (1 °F).^[39] As the temperature of the atmosphere increases, the capacity to hold water increases, leading to stronger storms and higher rainfall amounts.^[39]

As they move north, Atlantic hurricanes typically are forced east and out to sea by the jet stream's prevailing winds.^[40] In Sandy's case, this typical pattern was blocked by a ridge of high pressure over Greenland resulting in a negative North Atlantic Oscillation, forming a kink in the jet stream, causing it to double back on itself off the East Coast. Sandy was caught up in this northwesterly flow.^[40] The blocking pattern over Greenland also stalled an arctic front which combined with the cyclone.^[40] Mark Fischetti of Scientific American said that the jet stream's unusual shape was caused by the melting of Arctic ice.^[41] Jeff Masters of Weather Underground said that three studies in 2011 found "that the recent record decline in Arctic sea ice could be responsible, since this heats up the pole, altering the Equator-to-pole temperature difference, forcing the jet stream to slow down, meander, and get stuck in large loops."^[40] Trenberth said that while a negative North Atlantic Oscillation and a blocking anticyclone were in place, the null hypothesis remained that this was just the natural variability of weather.^[37] Sea level at New York and along the New Jersey coast has increased by nearly a foot over the last hundred years,^[42] which contributed to the storm surge.^[43] Harvard geologist Daniel P. Schrag calls Hurricane Sandy's 13-foot storm surge an example of what will, by mid-century, be the "new norm on the Eastern seaboard".^[44]

Preparations

Caribbean and Bermuda

After the storm became a tropical cyclone on October 22, the Government of Jamaica issued a tropical storm watch for the entire island.^[45] Early on October 23, the watch was replaced with a tropical storm warning and a hurricane watch was issued.^[46] At 1500 UTC, the hurricane watch was upgraded to a hurricane warning, while the tropical storm warning was discontinued.^[47] In preparation of the storm, many residents stocked up on supplies and reinforced roofing material. Acting Prime Minister Peter Phillips urged people to take this storm seriously, and also to take care of their neighbors, especially the elderly, children, and disabled. Government officials shut down schools, government buildings, and the airport in Kingston on the day prior to the arrival of Sandy. Meanwhile, numerous and early curfews were put in place to protect residents, properties, and to prevent crime.^[48] Shortly after Jamaica issued its first watch on October 22, theGovernment of Haiti issued a tropical storm watch for Haiti.^[49] By late October 23, it was modified to a tropical storm warning.^[50]

The Government of Cuba posted a hurricane watch for the Cuban Provinces of Camagüey, Granma, Guantánamo, Holguín, Las Tunas, and Santiago de Cuba at 1500 UTC on October 23.^[47] Only three hours later, the hurricane watch was switched to a hurricane warning.^[51] The Government of the Bahamas, at 1500 UTC on October 23, issued a tropical storm watch for several Bahamian islands, including the Acklins, Cat Island, Crooked Island, Exuma, Inagua, Long Cay, Long Island, Mayaguana, Ragged Island, Rum Cay, and San Salvador Island.^[47] Later that day, another tropical storm watch was issued for Abaco Islands, Andros Island, the Berry Islands, Bimini, Eleuthera, Grand Bahama, and New Providence.^[51] By early on October 24, the tropical storm watch for Cat Island, Exuma, Long Island, Rum Cay, and San Salvador was upgraded to a tropical storm warning.^[52]

At 1515 UTC on October 26, the Bermuda Weather Service issued a tropical storm watch for Bermuda, reflecting the enormous size of the storm and the anticipated wide-reaching impacts.^[53]