NOAA's Climate Prediction Center has issued its annual Atlantic hurricane season outlook. The season runs from June 1 through Nov. 30.
This year, NOAA (National Oceanic and Atmospheric Administration) forecasts an above-normal hurricane season with a 70 percent likelihood of 11 to 17 named storms, five to nine hurricanes and two to four major hurricanes (category 3, 4 or 5; winds of 111 mph or higher). An average season produces 12 named storms, six hurricanes and three major hurricanes.
“The outlook reflects our expectation of a weak or nonexistent El Nino, near- or above-average sea surface temperatures across the tropical Atlantic Ocean and Caribbean Sea, and average or weaker-than-average vertical wind shear in that same region,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with NOAA’s Climate Prediction Center.
Strong El Ninos and wind shear typically suppress the development of Atlantic hurricanes, so the prediction for weak conditions points to more hurricane activity this year. Also, warmer sea surface temperatures tend to fuel hurricanes as they move across the ocean. However, the climate models are showing considerable uncertainty, which is reflected in the comparable probabilities for an above-normal and near-normal season.
Even though Atlantic hurricane season does not start until June 1, there's already been one tropical storm, Arlene, a rare pre-season storm that formed over the eastern Atlantic in April. This storm is already included in the 2017 season forecast.
But having tropical activity before the official start of the hurricane season does not necessarily mean it will be a busy hurricane season. Also, having a busy hurricane season does not mean there will be a lot of land-falling hurricanes or tropical storms in the United States.
For example, in 1992, the first named storm did not form until August, and it was Hurricane Andrew, which devastated South Florida. In another example, the 2010 hurricane season was above average with 19 named storms and 12 hurricanes in the Atlantic Basin. Despite the busy season, not a single hurricane and only one tropical storm made landfall in the United States.