With the peak of the 2014 hurricane season approaching, researchers at Colorado State University reaffirmed their June forecast for a relatively quiet summer.
CSU meteorologists Phil Klotzbach and William Gray said today they think nine tropical storms will form in the Atlantic Basin — which includes the Atlantic Ocean, Gulf of Mexico and Caribbean Sea — between August 1 and the end of the hurricane season on November 30. Of those storms, Klotzbach and Gray think four tropical storms will strengthen into hurricanes with winds of at least 74 mph.
The forecasters think one of those hurricanes will intensify into a major hurricane with peak winds exceeding 110 mph.
One hurricane formed earlier this month. That storm, Hurricane Arthur, became a category two hurricane on the Saffir-Simpson Scale, which rates hurricanes by wind speeds and destructive potential. A category two hurricane has peak winds ranging from 96 mph to 110 mph.
Hurricane Arthur made landfall near Cape Lookout, North Carolina on July 3 with peak winds of about 101 mph. The storm then curved back out to sea but caused flooding along the U.S. east coast as it moved to a second landfall at Nova Scotia on July 5.
In a prepared statement from CSU, Klotzbach said conditions in the Atlantic are not favorable for hurricane formation this summer and aren’t expected to improve.
Hurricanes draw their energy from seawater that has been heated to at least 80 degrees Fahrenheit. Water that is even a few degrees cooler will not sustain a tropical storm.
Upper level winds, known as wind shear, can also inhibit hurricane formation. If a hurricane encounters wind shear, it will quickly begin losing intensity.
“The tropical Atlantic remains anomalously cool, and vertical shear throughout the basin remains at above-average levels,” Klotzbach said. “In addition, the chances of a weak to moderate El Niño event during the peak of the hurricane season remain elevated. Historical data indicate fewer storms form in these conditions.”
An El Niño occurs when waters in the south central and southeastern Pacific Ocean are unusually warm. One of the effects of an El Niño is stronger than usual wind shear over the Atlantic Ocean.
The likelihood that tropical storms will form in the Atlantic starts increasing in August, after the waters have been absorbing heat for several months. The peak of the hurricane season is September 10, when conditions usually are most favorable for storm formation.
After September, hurricanes are more likely to form in the Caribbean Sea.
Willie Drye has been writing about hurricanes and other topics for National Geographic News since 2003. Visit his blog, Drye Goods.