Hurricane Forecast: No Letup Till November

Willie Drye
for National Geographic News

September 13, 2005

With New Orleans in ruins after Hurricane Katrina and North Carolina
threatened by Hurricane Ophelia, U.S. coastal residents are getting
more bad news: The rest of the 2005 hurricane season probably will be
very active.

A team led by William Gray, a professor of meteorology at Colorado State University, expects four more hurricanes will form in September and two in October.

The scientists predict that two of the September hurricanes will be major storms with winds of at least 111 miles an hour (178 kilometers an hour). One of the October hurricanes is also expected to be a major storm.

Gray, a pioneer in long-range hurricane forecasting, and research associates Phil Klotzbach and William Thorson released their prediction earlier this month.

"We anticipate that the 2005 Atlantic basin tropical cyclone season will be much higher than the full season activity we anticipated in our early December, early April, and early June forecasts," the trio wrote.

"We expect that by the time the 2005 hurricane season is over, we will witness seasonal tropical cyclone activity at near record levels."

Record Season

This season already has been one for the record books. Although the hurricane season runs from June 1 to November 30, the most powerful storms usually don't start forming until around mid-August. September 10 is considered the peak of the season.

This year, however, was an exception. Five hurricanes formed in July. Two of them—Hurricane Dennis and Hurricane Emily—became the most powerful hurricanes on record for that month.

The 2005 season will also dwarf the cost of destruction caused by previous hurricanes because of one monster storm—Hurricane Katrina. The tempest struck the coasts of Louisiana and Mississippi on August 29, sending a massive storm surge that pounded against the levees intended to protect New Orleans from flooding.

The levees gave way after the hurricane's eye had passed, flooding most of the city and causing unprecedented damage. Katrina then slammed into Mississippi with only slightly less force and inflicted catastrophic damage to the cities of Gulfport and Biloxi.

Authorities ordered all of New Orleans's approximately 500,000 residents to evacuate the city. The breaks in the levees have since been patched and water is being pumped out of the city. But it could be many months before residents can return.

Authorities are still tabulating an official death toll from Katrina. Early fears that as many as 10,000 had been killed seem to be ebbing as rescue workers are finding fewer bodies.

Still, the number killed in Louisiana, Mississippi, Alabama and Florida has topped 500—far more than have been killed by a hurricane in the U.S. in decades.

The cost of the damage inflicted on the Gulf Coast by Hurricane Katrina is expected to dwarf that of the 1992 season, when Hurricane Andrew claimed the highest damage total until this year.

Andrew's eye went ashore just south of Miami in August 1992. The storm's winds, which exceeded 155 miles an hour (249 kilometers an hour), cut a swath of devastation across densely populated southern Dade County.

Hurricane Andrew caused damage totaling about 35 billion dollars (U.S.) when adjusted for inflation.

The cost of Hurricane Katrina is only beginning to be calculated, but it's expected to be staggering. Early estimates predict that the cost will easily exceed 200 billion dollars and could approach 300 billion dollars.

Decade-Long Trend

The devastating and deadly 2005 hurricane season continues a trend of stormier summers that began in 1995. Gray and other research meteorologists say that active hurricane seasons are cyclical. The cycles of active seasons can last several decades.

The most active hurricane season on record is 1933. That year 21 tropical storms formed. Of those storms, nine developed into hurricanes, and five of them became major hurricanes with winds of at least 111 miles an hour (249 kilometers an hour).

The second-most active season on record was 1995, when 19 tropical storms formed.

Gray and his colleagues say the alternating cycles of active and less active hurricane seasons are caused by fluctuations in the salt content of ocean water. When the water has a higher level of salt—as the Atlantic does now—the water is warmer. That, in turn, spawns more tropical storms.

Some meteorologists think that global warming is contributing to the increase in hurricanes and making the storms more intense.

But Gray disagrees with this theory. When the total number of tropical storms and hurricanes around the world are added up, he says, "there has actually been a slight decrease since 1995."

Willie Drye is the author of Storm of the Century: The Labor Day Hurricane of 1935, published by National Geographic Books.

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