Ivan the Terrible

Forecasters: More Hurricanes May Be on Way
Fri Sep 17, 2:31 PM ET Add U.S. National - AP to My Yahoo!
By JOSEPH B. VERRENGIA, AP Science Writer

Ivan, Frances and Charley delivered three staggering blows to the Gulf Coast and Florida, as well as Caribbean island nations, all in just five weeks. Now here comes Jeanne, which could be lashing north Florida and Georgia by Monday. Homeowners ritualistically re-hammering the same plywood over their windows figure it can't get much worse, right?

Brace yourselves: Scientists say 65 million Americans living on the Gulf and Atlantic coasts should expect weather like this for another 30 years. Maybe more.

Sure, it's hurricane season and storms happen. But counting Alex, which swamped the Carolinas in August, that's five in six weeks. And that doesn't include tropical storms Bonnie, Gaston, Earl and Hermine.

"I don't remember this happening before in such a short period of time," National Hurricane Center (news - web sites) director Max Mayfield told reporters, "and the season is only half-over."

It might be a generation before hurricane weather slips back into a quiet phase, he and other experts say.

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Hurricanes reflect the complex dance between the atmosphere and the oceans.

When the Pacific Ocean cools during the La Nina climate phenomenon, the Atlantic warms up, and more hurricanes are the result. Over the Atlantic, wind shear that knocks down rising storms tend to slacken, while humid westerly winds from Africa's bulge grow stronger.

Scientists look for large pools in subtropical ocean where water is at least 81 degrees Fahrenheit. The warm sea heats the air in a rising column, creating a center of moist low pressure.

Trade winds rush in toward this depression. Combined with the planet's rotation, they spin clouds counterclockwise around this steamy core, or "eye" of the storm.

Most scientists agree that global warming plays little or no role in the number of storms in the current hurricane cycle.

Global climate models show that air pollution from industry and traffic will drive up average world temperatures by a degree or two this century. All that extra heat could fuel more stormy weather. And local evidence of temperatures rising may already be apparent with some glaciers melting and spring flowers blooming early. But so far, climate change is too uncertain and today's hurricane patterns are too complex to draw a connection.

"I don't think the warming now is anywhere near enough to account for the increase in hurricanes that we're seeing," said Robert Gall of the National Center for Atmospheric Research in Boulder, Colo. "To me, this is just a natural variation in the frequency of hurricanes."

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