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A record number of consecutive hurricanes made landfall on the U.S. East Coast this year, making it one of the most active storm seasons ever, government meteorologists report today.
The Atlantic hurricane season, which began June 1 and ends Sunday, delivered a total of 16 named storms, including six consecutive tropical cyclones — Dolly, Edouard, Fay, Gustav, Hanna and Ike — to the mainland. Eight were hurricanes, five of which were major storms of Category 3 strength or more, the National Hurricane Center says. (Category 3 storms carry winds of 111-to-130 miles, or 178-to-209 kilometers, per hour.)
The tally mirrors the center's original prediction of 16 named tempests. Still, this year was more active than usual; a typical season has 11 named storms, six hurricanes and two major hurricanes, according to the weather watchers.
The blustery year is due to lingering, light wind shears from La Niña (which began in fall 2007 and ended in June) and a phenomenon called the Atlantic Multidecadal Oscillation that produces alternatingly warm and cold sea surface temperatures. Temperatures vary across the tropical Atlantic, but overall, they were about one degree warmer than usual during the season's peak, hurricane forecaster Gerry Bell tells us.
The Atlantic Multidecadal Oscillation is "a major factor influencing hurricane activity," Bell says. We're just 13 years into a warm period that could last 25 to 40 years, he says. Right now, the oscillation is producing stronger monsoons in West Africa and weaker rainfall in the Amazon basin. Those effects are associated with a lower wind shear, which favors hurricanes that require little change in wind patterns to form.
The Eastern Pacific hurricane season on the West Coast and Hawaii brought 16 tropical storms, seven hurricanes and two major hurricanes, below the average 15 tropical storms, nine hurricanes and four major hurricanes there, Bell says.
For more on hurricanes, see our in-depth report.
Track map of 2008 Atlantic hurricane season/NOAA