(National Hurricane Center )
Forecasters are expecting the fewest Atlantic hurricanes and tropical storms since 2009, particularly if the weather phenomenon El Niño develops by the heart of the hurricane season.
The National Oceanic and Atmospheric Administration is predicting nine to 15 named storms, down from 19 named storms during each of the past two hurricane seasons. That is consistent with recent predictions from other hurricane forecasters, calling for about 10 to 12 named storms.
Despite an early start to the hurricane seasons in both the Atlantic and Pacific oceans, there is no indication of a third consecutive active hurricane season, meteorologists said. Forecasters and emergency management officials warned the Eastern U.S. to remain on guard nonetheless.
"The bottom line here is to prepare," Robert Detrick, director of NOAA's Office of Oceanic and Atmospheric Research, said at a news conference Thursday. "It takes just one major landfalling hurricane to make a bad season," he added, giving the example of Hurricane Andrew in 1992, which devastated Florida during a quieter hurricane season.
NOAA's forecast predicts four to eight of the named storms will become hurricanes, with winds of at least 74 mph, and one to three of those will become major hurricanes with winds of at least 111 mph. That would be on par with the 2009 hurricane season, with three hurricanes and nine named storms.
Last month, AccuWeather.com forecasted a dozen named storms, including five hurricanes, while the Tropical Meteorology Project at Colorado State University predicted 10 named storms. The Tropical Meteorology Project's forecast was the only to suggest where storms could likely hit, giving a 31 percent chance that a major hurricane would strike somewhere along the East Coast.
For a clearer indication of how the Atlantic storm season could develop, meteorologists are watching water temperatures not just in the seas off Africa's west coast, but in the Pacific along the equator. That is where conditions for El Niño and La Niña phenomena develop, through anomalies in surface water temperatures.
A La Niña ended last month, and climatologists estimate a 50/50 chance that an El Niño could form by the end of summer. That would stymie hurricane formation by increasing wind shear, Detrick said. Westerly winds could come into the tropics more frequently, and clouds could become "tilted" toward the northeast, said Dan Kottlowski, expert senior meteorologist and lead hurricane forecaster for AccuWeather. He likened it to a spinning top – if the top is tilted, it doesn't spin as fast.
Meteorologists said the formation of Tropical Storm Alberto off the Carolina coast last week isn't an indication of increased storm activity, but it could help buoy storm tallies.
Phillip Klotzbach, a research scientist at the tropical meteorology project in Colorado, called Alberto "oddball stuff" and "an interesting curiosity."
"Early season activity doesn't relate much to the rest of the hurricane season," Klotzbach said.
But that doesn't mean the rest of the season is easy to predict. Once more evidence on the potential for an El Niño appears, the hurricane outlook will become more clear, he said.
"The big thing with this year's forecast is uncertainty," Klotzbach said. "Obviously there's uncertainty with every forecast, but this one is pretty challenging."