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CSU Forecasters Expect Below-Average Hurricane Season

Meteorologists at Colorado State University think cooler ocean waters and the formation of a phenomenon known as El Niño will make the 2015 hurricane season much quieter than usual.

The CSU preseason forecast released today predicts seven named tropical storms will form in the Atlantic Basin — which includes the Atlantic Ocean, Gulf of Mexico and Caribbean Sea — between June 1 and November 30. Three of those storms are expected to become hurricanes with winds of at least 74 mph, and one of the hurricanes is expected to strengthen into a major storm with winds exceeding 110 mph.

CSU meteorologist Phil Klotzbach said the Atlantic is much cooler than usual as the summer hurricane season approaches. Hurricanes draw their power from seawater that has been heated to at least 80 degrees Fahrenheit.

The probable formation of an El Niño also is likely to suppress hurricane formation, Klotzbach said.

An El Niño occurs when sea surface temperatures in the equatorial Pacific Ocean are unusually warm. The warmer water creates atmospheric winds known as wind shear that makes it difficult for hurricanes to form in the Atlantic.

The CSU forecast also said there was only about a 28 percent chance that a major hurricane would make landfall somewhere on the U.S. coast between Texas and Maine. The average chance of landfall for the past 100 years is about 52 percent.

The likelihood of a hurricane striking the U.S. East Coast was even lower at 15 percent, the forecasters said. During the past century, the average chance of a hurricane making landfall there is about 31 percent.

There is about a 15 percent chance of a major hurricane striking the Gulf Coast from the Florida Panhandle to the Texas-Mexico border, and about a 22 percent chance of a major storm making landfall in the Caribbean. The averages for those regions during the past century have been about 30 percent and about 42 percent, respectively.

Despite the forecast for a relatively quiet summer and fall, Klotzbach cautioned that dangerous and powerful hurricanes sometimes form during otherwise quiet seasons.

“It takes only one landfall event near you to make this an active season,” Klotzbach said.

Perhaps the most famous example of a killer storm in a quiet season was Hurricane Andrew, which made landfall near Miami with sustained winds of at least 175 mph in August 1992. That season was nearly identical to the forecast for 2015. Seven tropical storms formed in 1992, and Andrew was the only major hurricane among the four that formed.

CSU will update its 2015 forecast on June 1, July 1 and August 3. The full preseason report can be seen here.

Willie Drye has been writing about hurricanes and other topics for National Geographic News since 2003. Follow him on Twitter.