Hurricane Season May Fizzle Further Due to El Nino

Willie Drye
for National Geographic News

September 05, 2006

Hurricane forecasters believe a weather phenomenon called El Niño
may make the rest of the 2006 Atlantic hurricane season quieter than
originally predicted.

The National Oceanic and Atmospheric Administration defines El Niño as a disruption of the ocean and atmospheric system in the tropical Pacific Ocean.

When this happens, there can be far-reaching consequences, including droughts in some places and flooding in others. But it can also suppress hurricane formation in the Atlantic. The last time an El Niño occurred was 1997.

In a prepared statement, Colorado State University forecasters Phil Klotzbach and William Gray in Fort Collins say they see indications that an El Niño might form this fall.

The pair has therefore reduced for the second time the number of tropical storms they think will form in the Atlantic Basin, which includes the Caribbean Sea and Gulf of Mexico.

The updated forecast, released September 1, predicts that 13 named tropical storms will form, with winds of at least 39 miles (63 kilometers) an hour.

Of those storms, the forecasters say, five will grow into hurricanes with winds of at least 74 miles (119 kilometers) an hour, and two will become major hurricanes with winds exceeding 111 miles (179 kilometers) an hour.

So far six tropical storms have formed since the hurricane season began on June 1. The most recent of these is Florence, which strengthened into a tropical storm this afternoon.

Only one storm this season has become a hurricane. Ernesto briefly reached that status during its trek across the Caribbean Sea last month.

Ernesto later made landfalls in Haiti, Cuba, Florida, and North Carolina as a tropical storm.

The hurricane season ends November 30.

All Dried Out

The 2006 season was initially expected to be much more active. Early Colorado State University forecasts predicted as many as 17 tropical storms would form. Those storms were expected to produce nine hurricanes, five of them major hurricanes.

Those numbers were revised downward early last month to 15 named storms and seven hurricanes, including three major hurricanes.

Those predictions were especially worrisome to residents on the U.S. Atlantic and Gulf coasts because of last year's explosive hurricane season. The 2005 season set a record, with 28 named storms forming and four very intense hurricanes—Dennis, Katrina, Rita, and Wilma—making landfall.

However, Gray and Klotzbach say they see indications that the rest of the storm season will be quieter than expected.

"We predict September and October will exhibit characteristics of a more average year, based on the activity so far this season and climate signals through August," Klotzbach said.

Besides the possible El Niño event, the forecasters say drier air over the tropical Atlantic—where hurricanes are born—will decrease storm formation.

Hurricanes draw their energy from warm ocean waters and warm, moist air. (See an interactive feature of how hurricanes form.)

Gray and Klotzbach say that dust carried over the Atlantic from western Africa will inhibit storm formation as well. (Related: "Hurricane Secrets May Be Revealed by African Thunderstorms" [August 2006].)

Not Out of the Woods

Still, the forecasters think most of the season's remaining activity will occur this month. They predict five tropical storms will produce three hurricanes, including two major hurricanes, by the end of September.

October will be below average, with two tropical storms and one minor hurricane, they predict.

Gray and Klotzbach say the U.S. was unusually lucky during the past few decades, because so few major hurricanes made landfall. From 1995 to 2003, 32 major hurricanes formed in the Atlantic, but only 3 of those made landfall in the U.S.

Since 2004, however, 13 major hurricanes have formed, and 7 have come ashore in the U.S. One of those—Hurricane Katrina, which struck Louisiana and Mississippi in August 2005—was the most costly hurricane in U.S. history (see complete Hurricane Katrina coverage).

"For many years, we have been warning of the return of major hurricane landfall events similar to what was experienced in the 1940s through the 1960s," Klotzbach said in the statement. "We also warned that destruction was likely to be higher than was previously experienced due to increased coastal population and wealth per capita."

"The activity of these two years was unusual but well within natural bounds of hurricane variation," Gray said. "This is how nature sometimes works."

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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