Experts: More Hurricanes Headed East

W A S H I N G T O N, July 20 -- The winds of change are threatening millionsof people living along America's East and Gulf coasts.

The increase in the number of hurricanes seen in recent years islikely to continue, perhaps for decades, a team of weatherresearchers reports in today's issue of the journal Science.

The waters of the North Atlantic Ocean have been warming inrecent years, providing increased energy to fuel these massivestorms, according to the group led by Stanley B. Goldenberg of theNational Oceanic and Atmospheric Administration's HurricaneResearch Division in Miami.

At the same time, the scientists found a decline in wind shear,which can inhibit development of the storms. Wind shear occurs whenwind speeds differ sharply at different altitudes and powerfulwinds high in the sky can prevent the vertical development ofstorms below them.

"When we see this combination, we better be prepared for a verybusy period for hurricane activity," Goldenberg said.

Alternating Hurricane Periods

The group also noted what appears to be a cycle of periods withmore hurricanes alternating with quieter times.

The years from 1995 to 2000 were among the most active inhistory for hurricanes, following a quiet period that began in the1960s.

"Looking at the changes in oceanic and atmospheric conditions,we think this shift is due to a natural ocean cycle called theAtlantic Multidecadal Mode, a North Atlantic and Caribbean Seasurface temperature shift between warm and cool phases that lasts25 to 40 years each," said Alberto M. Mestas-Nunez of NOAA'sCooperative Institute for Marine and Atmospheric Studies at theUniversity of Miami.

"The data suggest that we are in the beginning of a warmAtlantic phase and thus an active Atlantic hurricane era may beunder way, similar to that last seen from the late 1920s to thelate 1960s," he said.

That reinforces a report earlier this year by James B. Elsner ofFlorida State University, who found that busy and quiet hurricaneperiods in the Atlantic and Gulf of Mexico appeared to alternate.He said a period of more than normal storms is getting under way.