'Canes Give U.S. a Lashing
Statistics say it all for last years' storms. Measured by insured losses, the 2004 hurricane season was a rare one-in-70-year event. Four hurricanes (Charley, Frances, Ivan and Jeanne) swept through Florida, and Hurricane Gaston made landfall in South Carolina.
Only three other seasons in the United States since 1900 involved five or more landfalls. For a season when three major storms (Category 3 or greater) hit Florida, there is no precedent since 1851.
To explain these historic numbers, Richard Pasch, a hurricane expert at the National Hurricane Center, points to two factors. First, the continuation of the warm-water cycle in the tropical Atlantic, which has been on the upswing since 1995. Warm water makes for a fertile hurricane growing field, hence the 15 named storms that sprouted in the Atlantic Basin in 2004.
Tepid ocean water and the resulting tropical storms aren't such a threat to life and limb, though, if the cyclones stay out to sea, which was generally the case in the last nine years of high-hurricane activity. In 2004, they shifted, and with the help of persistent high pressure near the U.S. east coast, funneled the storms toward the southeast. Florida was like a pin in a PBA bowling tournament.
Another factor, says Phil Klotzbach, lead research associate for Dr. William Gray's hurricane-forecasting outfit at Colorado State University, is the state of El Niņo conditions.
When El Niņo is strong in the Pacific, it whips up vertical wind sheer in the Atlantic that tears apart storms before they can develop. A weak or neutral El Niņo, on the other hand, has little effect. Last year, El Niņo was spinning in weak mode. "What happened last year is different than the last nine years," Pasch says. "It all changed last year for reasons that aren't very well understood."
Ominously, the same factors seem to be at work for 2005. "We're looking at very warm waters again, even warmer than last year," Pasch says, "and that certainly doesn't bode well."
August 1, 2005
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