Storms Haven't Traveled Very Far

TAMPA - At this hurricane season's midpoint, few storms have emerged from the steamy stretches of the tropical Atlantic, the normal birthplace of hurricanes in midsummer.

Instead, 10 of this year's 13 named storms formed much closer to the U.S. mainland, including Hurricane Katrina, which grew into a hurricane in the eastern Bahamas two days before hitting Florida, then moving to smash the northern Gulf Coast.

This season, conditions from the Leeward Islands eastward to Cape Verde just off the African coast kept whirling masses of thunderstorms from developing into hurricanes or tropical storms.

The vast expanse of empty ocean usually becomes the prime breeding ground for storms from August to mid- October, the busiest part of hurricane season.

The season has yet to produce a classic Cape Verde hurricane - one that forms far in the eastern Atlantic and tracks westward for days.

Don't expect calm in the far eastern Atlantic to last.

Conditions that hindered hurricane formation in the Atlantic can change quickly, said Max Mayfield, director of the National Hurricane Center.

``I'd be very surprised not to see a couple of Cape Verde systems this year,'' he said.

Ten of this year's storms formed west of Puerto Rico, considered the dividing line between the eastern and western parts of the Atlantic hurricane basin.

Three named storms formed in the eastern Atlantic. Hurricane Irene curved off the U.S. East Coast. Tropical Storm Lee posed no threat to land, nor does Tropical Storm Maria seem poised to.

``The western part of the basin had been more conducive to storms spinning up,'' said James Elsner, Florida State University geography professor with the Center for Ocean- Atmospheric Prediction Studies.

In August, September and early October, water temperatures hit the mid-80s in the Atlantic, and winds two to five miles above the ocean that disrupt developing storms diminish.

Those upper-level winds called shear throttled many of the storms trying to develop in the Atlantic, but not in the usual way.

Normally coming from the west, the winds this year are moving from the east, blowing so strongly they slice developing hurricanes in half.

``You don't normally see that,'' Mayfield said.

Research last year and this season might reveal another reason hurricanes have trouble forming in the Atlantic - massive dust storms from the Sahara crossing the Atlantic.

``These big Saharan dust storms come every four or five days and have superdry air,'' said Jason Dunion, meteorologist with the federal government's Hurricane Research Division based in Miami.

Storms or tropical waves moving through the clouds of fine dust start taking in the dry air about a mile above the earth, sapping their energy.

``Dry air is really a hurricane killer,'' Dunion said. ``If you want to knock out a hurricane, shoot it with dry air at that altitude.''

Some of the tropical waves that fizzled this season encountered the Saharan air, he said.

Researchers cannot predict how much the dry air will affect each developing hurricane.

Mayfield said research into the Saharan air masses shows promise but is not ready to become part of the hurricane center's predictions.

Unfortunately for the battered U.S. mainland, the dust storms tend to become less frequent in September and rarely reach into the western Atlantic, Dunion said.

Reporter Neil Johnson can be reached at (352) 544-5214.