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Hurricane Season Is About to Get Stronger After Years of Calmer Waters

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Forecasters warned Thursday that the eastern United States will likely experience a stronger than normal hurricane season this year, with as many as four major hurricanes forming over the Atlantic.

The prediction from federal forecasters at the National Oceanic and Atmospheric Administration (NOAA) suggests a 45% chance for an “above-normal” hurricane season, a 35% chance of a “near-normal” season and a 20% chance of a “below-normal” season. Agency officials said they expect a total of five to nine hurricanes with wind speeds of at least 74 miles per hour. They expect as many as four of them to turn into major hurricanes with winds of at least 111 mph.

“We’re expecting a lot of storms this season,” Gerry Bell, lead seasonal hurricane forecaster with NOAA’s Climate Prediction Center, told reporters on a conference call. “Whether it’s above normal or near normal, that’s a lot of hurricanes.”

The prediction follows a decade-long period without a storm that meets the criteria of a major hurricane hitting the U.S., an occurrence that has left scientists scratching their heads. Nonetheless, several storms including Hurricane Sandy and Hurricane Matthew, have taken lives and cost billions in damage. As in past years, officials are emphasizing the need for Americans who live in areas affected by hurricanes to prepare regardless of the outlook in advance of the official beginning of hurricane season in June.

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Forecasters cited a “weak or non-existent” El Niño along with relatively warm sea-surface temperatures in the the tropical Atlantic as key factors behind their prediction. El Niño increases wind shear, a measure of difference in wind speed, and stabilizes the atmosphere making it more difficult for large storms to develop.

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“What does the forecast mean to FEMA?” said acting Federal Emergency Management Agency (FEMA) Administrator Robert J. Fenton, Jr. “It really only takes one storm.”

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Write to Justin Worland at justin.worland@time.com