for National Geographic News
Before the 2009 Atlantic hurricane season kicked off on June 1, forecasters were calling for 12 named storms, with about half developing into hurricanes.
Now, about two months into the season, zero storms have formed in the Atlantic.
That's because El Niño conditions over the Pacific Ocean have so far kept a lid on the 2009 hurricane season, experts say.
Still, meteorologists warn that a monster hurricane could be spawned before the season ends on November 30.
"Oases of favorable conditions" could exist in the Atlantic Basin long enough to allow a powerful storm to form, said Keith Blackwell, a meteorologist at the University of South Alabama's Coastal Weather Research Center in Mobile.
"It's very plausible that we still could get one or two intense hurricanes this year," Blackwell said. "And it only takes one to make it a bad season."
"Monster" to Come?
An El Niño is an unusually warm flow of water that sometimes forms off the northwestern coast of South America. The phenomenon causes a band of upper-level prevailing winds known as the jet stream to shift southward.
When the jet stream blows over the Atlantic Basin—which includes the Caribbean Sea and the Gulf of Mexico—the current creates wind shear, upper-level winds that can disrupt hurricane formation and development.
El Niño conditions have developed over the past few months, and that's the most likely reason that the start of the season has been relatively quiet, experts say.
Still, Blackwell noted, an El Niño also formed in 1992, and that year saw the birth of Hurricane Andrew, the third most powerful hurricane to strike the U.S. in recorded history.
Andrew, the 1992 Atlantic season's first named tropical storm, formed as a tropical depression on August 16. It made landfall as a Category 5 storm on August 24 just south of Miami, Florida, with winds of about 165 miles (265.5 kilometers) an hour.
Blackwell added that El Niño conditions suppress hurricane formation mostly in traditional spawning grounds in the Caribbean Sea and tropical Atlantic waters. But powerful hurricanes can form elsewhere.
Hurricane Alicia, for example, formed in mid-August 1983 just off the Louisiana coast during an El Niño. That storm later struck Houston, Texas, with 115-mile-an-hour (185-kilometer-an-hour) winds.
Based on the current El Niño conditions, Colorado State University meteorologists William Gray and Phil Klotzbach this week issued an updated hurricane forecast, which calls for 2009 to be a below-average season.
The pair predicts that this season will see just ten named tropical storms in the Atlantic.
Four of those storms are expected to develop into hurricanes, with winds of at least 74 miles (119 kilometers) an hour. Two will become major hurricanes, with winds exceeding 110 miles (177 kilometers) an hour, the meteorologists say.
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