May 24 (Bloomberg) -- The 2012 Atlantic hurricane season may be near normal, producing nine to 15 named storms before it ends Nov. 30, said Gerry Bell, lead hurricane forecaster at the U.S. Climate Prediction Center.
Of those storms, four to eight are expected to become hurricanes with winds of at least 74 miles (119 kilometers) per hour, and as many as three may develop into major systems with winds in excess of 111 mph.
“While this is less than we have seen in some of these more active seasons, it’s still a lot of activity, so no one is off the hook at all,” Bell said on a conference call. One tropical storm has already formed this year even though the season officially starts June 1.
Atlantic hurricanes are the costliest weather-related disasters in the U.S. and pose a threat to oil and gas production, agriculture and population centers in the eastern half of the country.
Three of the top 10 most expensive natural disasters from 1980 to 2011 were hurricanes, including Katrina, which was the most damaging event on the list, according to the Insurance Information Institute in New York. Seven of the 10 costliest hurricanes hit Florida, according to the Insurance Institute.
Florida, the second-largest producer of oranges behind Brazil, is directly in the path of tropical systems moving across the Atlantic. The Gulf of Mexico is home to 29 percent of U.S. oil output, 6.4 percent of gas production and 40 percent of refining capacity.
Katrina and Rita
Katrina and Rita killed more than 1,800 people, caused $91 billion in damage and destroyed 113 energy platforms in the Gulf in 2005. The total natural gas production lost in the 10 months following Katrina was equivalent to 22 percent of yearly output in U.S. Gulf waters, the department said. Gas futures hit a record $15.78 in December 2005.
An average Atlantic season produces 12 named storms, those with winds of 39 mph or higher. Bell said the biggest influence on this year’s hurricane activity in the Atlantic will be an El Nino, a warming of the central Pacific. If one emerges in September or October, it could limit the number of storms.
El Nino increases the amount of wind shear that occurs in the Atlantic. These winds tear at storms, preventing them from forming. More storms form when the Pacific is cool or neutral, as it is now, Bell said.
In 2010 and 2011, 19 storms grew in the Atlantic, tying the seasons with 1995 and 1887 as third-most active based on records dating to 1851. In 2005, 28 storms formed, the most ever.
The 30-year average for hurricanes is six, three of them major systems.
While those Category 3 or higher storms are among the most dangerous, National Hurricane Center Director Bill Read said the public needs to be wary of all.
“There is no such thing as just a tropical storm,” said Read, who is stepping down as head of the Miami-based center on June 2 and will be replaced by Rick Knabb.
Reed said a tropical storm with 70 mph winds can destroy a city’s power grid after hammering it for several hours. Heavy rain from systems moving inland can cause life-threatening floods and destroy homes and businesses.
In 2011, Hurricane Irene struck the U.S. East Coast as a Category 1 storm and killed at least 45 people and caused $7.3 billion in damage, including devastating floods in Vermont and western Massachusetts that washed away bridges and leveled homes. Irene’s name was retired from hurricane lists.
Bell said the forecasts represent the best estimate of what may happen based on sea surface temperatures, wind shear and other factors in the ocean and are accurate 70 percent of the time. Forecasters are getting better, though errors do occur.
“This is a seasonal hurricane outlook, not a statement of fact,” said Bell, whose office is in Camp Springs, Maryland.
In April, Colorado State University researchers who pioneered long-range hurricane forecasting predicted 10 storms would form, four of which would become hurricanes. Colorado State will update its outlook June 1.
The National Hurricane Center and the Storm Prediction Center are both parts of the National Oceanic and Atmospheric Administration.
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