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2007 Expected to Spawn Very Active Hurricane Season
Defying predictions, the 2006 Atlantic hurricane season fortunately did not produce a single landfall, but that could turn out to be the quiet before the storms if the forecast for the 2007 season released last week holds true.
This year’s hurricane season will be much more active than the average season from 1950 to 2000, Philip Klotzbach and William Gray from Colorado State University's Department of Atmospheric Science announced on April 3.
The forecasters are predicting nine hurricanes this year, compared to an average of 5.9, and five of those will be intense, at least a Category 3, compared to an average of 2.3. The probability of a major hurricane landfall in the U.S. is estimated to be about 140% of the long-period average, they said.
The hurricane forecast has been upwardly revised from the prior forecast in early December, they said, due largely to the rapid dissipation of El Nino that has occurred over the past couple of months. “We expect either neutral or weak-to-moderate La Nina conditions to be present during the upcoming hurricane season,” they said. “Tropical and North Atlantic sea surface temperatures remain well above their long-period averages.”
The 2006 season was only the 12th year since 1945 in which there were no hurricane landfalls along the U.S. coastline. There have only been two consecutive seasons without landfalls — 1981 to 1982 and 2000 to 2001. The most recent stretch was “especially impressive,” the meteorologists said, because the amount of hurricane activity during those years was well above average.
The most recent forecast also takes a look at the impact of global warming on unusually destructive seasons in 2004 with Charley, Frances, Ivan and Jeanne and in 2005 with Dennis, Katrina, Rita and Wilma, and it finds no link.
“Despite the global warming of the sea surface that has taken place over the last three decades, the global numbers of hurricanes and their intensity have not shown increases in recent years except for the Atlantic, where recent hurricane increases are likely a result of naturally occurring multi-decadal Atlantic Ocean circulation variances,” they said.
“We have no plausible physical reasons for believing that Atlantic hurricane frequency or intensity will change significantly if global ocean temperatures continue to rise,” they said.
“What made the 2004 to 2005 seasons so unusually destructive was not the high frequency of major hurricanes but the high percentage of major hurricanes which were steered over the U.S. coastline. The major U.S. hurricane landfall events of 2004 to 2005 were primarily a result of the favorable, upper-air steering currents present during these two years.”
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