The Atlantic hurricane season comes to a close today after producing 19 named storms for the third year in a row, an above-normal year with a damage toll that’s still being tallied.
The storms, named when winds reached at least 39 miles (63 kilometers) per hour, tied 2012 with 2011, 2010, 1995 and 1887 for third most-active on records dating to 1851, according to the National Oceanic and Atmospheric Administration. Ten of the systems became hurricanes and one grew into a major storm.
They killed hundreds in the U.S. and the Caribbean, curtailed oil and natural gas output and affected U.S. presidential politics from the conventions to the election.
“It’s going to go down in history as one of the most damaging years, as far as the United States is concerned,” said Dan Kottlowski, expert senior meteorologist at AccuWeather Inc. in State College, Pennsylvania. “This will be one of the most expensive, most damaging years of the hurricane seasons.”
Atlantic hurricanes are closely watched because of their potential impact in the Gulf of Mexico, home to 7 percent of U.S. natural gas output, 23 percent of its oil and 44 percent of its refining capacity, according to the Energy Department.
Hurricane Isaac, which made landfall in Louisiana as a Category 1 storm, shut as much as 95 percent of Gulf oil production and 73 percent of natural gas as companies evacuated offshore platforms and drilling rigs.
The U.S. has now gone seven years without being hit by a major hurricane, a Category 3 or stronger on a five-step scale with winds of at least 111 mph. A stretch that long is unprecedented in the 161-year record.
Even without a major system, the season spawned Hurricane Sandy, which transformed into a powerful winter storm that smashed the New Jersey coast and sent a surge of water into New York City. Homes were destroyed, mass transit shut and power knocked out to at least 8.5 million customers in 21 states.
Eight of the storms during the season, which started June 1, caused an estimated $35 billion in damage, according to Charles Watson, research and development director at Kinetic Analysis Corp., a hazard-research company in Silver Spring, Maryland.
The majority of that damage came from Sandy. Watson said the storm’s direct impact will be at least $25 billion and probably won’t exceed $32 billion. New York Governor Andrew Cuomo has estimated it may cost $33 billion in his state alone to clean up after Sandy.
Watson said 1992, 2004 and 2005 may rank higher in monetary damage in the modern era. Katrina hit the Gulf Coast in 2005, causing an estimated $125 billion in damage, according to the Federal Emergency Management Agency. Andrew hit Florida in 1992.
Sandy alone may exceed all of last year’s insured losses.
In 2011, natural disasters including an outbreak of tornadoes and a flood on the Mississippi River caused more than $35.9 billion in insured losses, surpassing the 2000-2010 annual average of $23.8 billion,said the Insurance Information Institute in New York.
Sandy may be the fifth-costliest weather disaster in the U.S. since 1980, said Jeff Masters, co-founder of Weather Underground in Ann Arbor, Michigan. The worst was Hurricane Katrina in 2005, followed by droughts in 2012, 1988 and 1980, he estimated Nov. 16.
Before Isaac’s impact could be felt on the energy markets, it had already forced its way into presidential politics. The storm’s brush with Florida caused the Republican Party to cancel some events at its national convention in Tampa. Sandy’s devastation put the presidential campaign on hold briefly.
In the past three years, 57 storms have developed in the Atlantic, second only to 2003-2005, when 59 formed, said Michael Schlacter, chief meteorologist with Weather 2000 Inc. in New York.
The numbers indicate that the Atlantic is still in the midst of pattern that has brought warmer seawater temperatures, and with them more hurricanes, since 1995, he said.
Schlacter said there may have been years before satellite coverage when storms were uncounted. Even so, “the three-year total is very impressive,” he said by telephone.
While the hurricane season officially ends today, tropical systems have formed in every month. The National Hurricane Center is monitoring a new low-pressure area in the Atlantic that has a 20 percent chance of developing into a storm in the next 48 hours.
Phil Klotzbach, a hurricane researcher at Colorado State University in Fort Collins, said the 2012 season was unusual because of a high number of weaker storms and only one becoming a major hurricane. That storm never reached land.
Colorado State predicted 15 storms would develop in the Atlantic basin, with five of them becoming hurricanes and two major hurricanes, Klotzbach said by telephone. The university pioneered seasonal hurricane forecasting 29 years ago.
In May, the U.S. Climate Prediction Center called for nine to 15 named storms in the Atlantic. The 30-year average is 12.
Forecasters under-predicted the season because they were certain an El Nino, or warming of the central Pacific Ocean, would take place, Klotzbach said earlier this week by telephone. The pattern causes an increase in Atlantic wind shear that can tear storms apart before they form.
While the Pacific’s waters edged toward the threshold of an El Nino, the phenomenon never formed.
“If you had told me that, I would have predicted a lot more,” Klotzbach said.
To contact the reporter on this story: Brian K. Sullivan in Boston at firstname.lastname@example.org
To contact the editor responsible for this story: Dan Stets at email@example.com