The 2012 Atlantic hurricane season will be “near normal” with nine to 15 tropical storms and four to eight of those will strengthen into hurricanes, the U.S. government weather agency predicted on Thursday.
One to three of those will grow into “major” hurricanes of Category 3 or higher on the Saffir-Simpson intensity scale, the National Oceanic and Atmospheric Administration said in its seasonal forecast. Major hurricanes have sustained winds of 178 kilometres per hour or higher and can cause devastating damage.
Hurricane season for the Atlantic Ocean, Caribbean Sea and Gulf of Mexico officially runs from June 1 to Nov. 30, but got off to an early start this year when Tropical Storm Alberto formed off the South Carolina coast last weekend. It turned away and fizzled without threatening land.
Forecasters said pre-season storms are not uncommon and there is not necessarily a connection between an early start and a busy season.
Seasonal forecasts cannot predict chances that a storm will affect any one area, but are a useful risk management tool for insurers, commodities traders and energy interests.
Over the last two decades, the average Atlantic season has brought 12 named storms with six hurricanes, including three major hurricanes.
NOAA said the region was still in the midst of a multi-decade active period for hurricanes but two factors could keep this year’s tally near normal.
Hurricanes feed on warm water, but sea surface temperatures in the eastern Atlantic are cooler this year. There is also strong wind shear in the region where most storms form, which tends to squelch storm formation.
“Another potentially competing climate factor would be El Nino if it develops by late summer to early fall. In that case, conditions could be less conducive for hurricane formation and intensification during the peak months (August-October) of the season, possibly shifting the activity toward the lower end of the predicted range,” said Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center.
El Nino, a period warming of the tropical Pacific, brings wind patterns that tend to weaken Atlantic hurricanes, and has far-reaching effects on global weather. It often brings heavy rain to Pacific islands and the west coast of South America and is associated with drought in Australia, Indonesia, the Philippines, Africa and India.