A cooler Atlantic Ocean will probably produce 10 named storms in the hurricane season that begins June 1, about half last year’s total, according to researchers at Colorado State University.
Of those systems, four will probably become hurricanes with winds of at least 74 miles (119 kilometers) per hour and two may grow into major storms with winds of 111 mph or more, according to the forecast.
“What we’re expecting right now is a somewhat below- average hurricane season compared to the 1981 to 2010 average,” said Phil Klotzbach, lead author of the forecast begun at the university 29 years ago by Bill Gray, a pioneer in long-range hurricane predictions. “The take-home message with all of our forecasts is that it is kind of our best estimate, but it only takes one storm to make it an active season for you.”
The season, which runs through Nov. 30, is closely watched because the storms are a threat to oil and natural gas interests in the Gulf of Mexico and agriculture in the South. The Gulf accounts for 29 percent of U.S. oil output and 40 percent of refining capacity, while Florida is the second-largest citrus producer behind Brazil.
Last year, Colorado State predicted in April that there would be 16 named storms. Nineteen developed, tying with 2010, 1995 and 1887 for the third-most active season, based on records dating back to 1851.
Klotzbach said larger weather patterns will probably have an impact on the number of storms in the Atlantic this year.
The Pacific Ocean may experience an El Nino warming, which will increase wind shear across the Atlantic, he said. Wind shear tears at the structure of hurricanes and can keep weaker systems from growing into larger storms.
The possibility of the Pacific warming to levels needed to create additional Atlantic shear is still uncertain, based on computer models, Klotzbach said.
The models are bad at making predictions about El Nino during the Northern Hemisphere’s spring from March to June, said Mike Halpert, deputy director of the U.S. Climate Prediction Center in Camp Springs, Maryland.
“This is absolutely the worst time of year to try to forecast,” Halpert said.
In addition to the warmth of the Pacific, temperatures at the surface of the Atlantic also play a role in determining how many hurricanes will form, Klotzbach said.
The Atlantic surface has cooled in part because of the weather pattern that left the eastern U.S. warmer than normal this past winter. A cooler Atlantic, especially off the coast of Africa, means there is less energy for storms to draw on as they develop, Klotzbach said.
Both companies predicted 11 storms for this year.
The average season produces 12 named systems, six of which become hurricanes with three developing into major storms, according to Dennis Feltgen, spokesman for the National Hurricane Center in Miami.
Irene, which went ashore in North Carolina, New Jersey and New York in August, was the first hurricane to strike the U.S. since Ike hit near Galveston, Texas, in 2008. There hasn’t been a major hurricane landfall since Wilma in 2005, the longest such stretch on record.
A storm gets a name when its winds reach 39 mph. Based on the averages from 1966 to 2009, the first of the season usually occurs by July 9 and the first hurricane by Aug. 10.
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