HURRICANE ONSLAUGHT

ALLISON. BARRY. CHANTAL. DEAN. Erin. Felix. Gabrielle. Humberto. Iris. Jerry. Karen. Luis. If residents of low-lying coastal areas are anxious this summer, they have a dozen reasons--and more are undoubtedly on the way. The hurricane season has not yet peaked, but menacing storms are already rumbling across the Atlantic Ocean one after another, like warplanes taking off from a carrier deck. Last week alone, four ominously swirling air masses zigzagged across satellite weather maps, packed so close together that it almost seemed they might merge to form a single monster storm. "You feel like you're standing in the line of fire," says Debby Sandberg, a high school math teacher in Miami. "You just keep waiting for something to hit."

No one under retirement age can recall a hurricane season quite like this. Not since 1933, says Bob Burpee, director of the National Hurricane Center near Miami, have so many hurricanes formed so early in the year. So far, 12 tropical storms have materialized off the west coast of Africa, six of which have grown into full-fledged hurricanes. The good news is that the damage to date--floods in the Carolinas, toppled trees and power lines in Central Florida, mud slides on the Caribbean island of Martinique--has been comparatively mild. The bad news is that more big storms are on their way, and before the end of November, when the season officially ends, one or two may yet slam into land with savage power.

But even if that doesn't happen, an ominous question remains: What, if anything, does this unnerving spate of extreme weather signify? Is it just a meteorological fluke, a one-season anomaly? Or could it signal a potentially devastating long-term trend? Atmospheric scientist William Gray of Colorado State University fears the answer is the latter.

Indeed, he notes, the large number of storms this year seems unusual only because the U.S. has experienced a hurricane lull for the past 25 years. A correction is now overdue and, when it comes, he warns, "We're going to see hurricane damage like we've never seen it before." It's not that the storms are necessarily getting more severe but that there has been massive population growth and an accompanying building boom along the Atlantic and Gulf coasts. More people live between Miami and Fort Lauderdale, notes political scientist Roger Pielke Jr. of the National Center for Atmospheric Research, than occupied the entire coastline from Texas to Virginia 60 years ago.

While boom-and-bust hurricane cycles lasting decades have been well documented, the reasons for them remain obscure. That's not the case for individual storms, though. Atlantic hurricanes inevitably get their start in Africa, where hot, dry air overlying the Sahara desert collides with cooler, moister air over the sub-Saharan region known as the Sahel. Under normal conditions, the collision produces eddies of low-pressure air that drift out over the ocean, where storm clouds begin to form. Most of the time, the clouds simply dump their load of rain and dissipate.