William Gray of Colorado State University now says there will be 12 named storms, eight hurricanes and four major hurricanes during the season that started last Thursday and ends November 30th.
That's an increase of one storm in each of the three categories.
Gray attributes the revision to his forecast first issued in December to a cooling weather pattern over Pacific Ocean waters near the equator known as La Nina.
"There has never been a case where the La Nina has remained as cold as at present," said Gray, an atmospheric science professor. "Cold water does nothing to disrupt the formation of hurricanes in the Atlantic Basin," which consists of the North Atlantic Ocean, Caribbean Sea and Gulf of Mexico.
CSU's 1999 forecast, of 14 named storms, nine hurricanes and four major hurricanes, was one of the more accurate in recent years, featuring 12 named storms, eight hurricanes and five major hurricanes.
Gray and his team of researchers make their predictions based on global ocean currents and temperatures, wind patterns, rainfall and historical data.
Gray said besides the La Nina phenomenon, other factors include earlier monsoons in Southwestern Africa and the arrangement of warm and cold waters in the Atlantic and Pacific oceans that make the conditions ripe for hurricanes.
He said residents along the U.S. Atlantic Coast, including peninsular Florida, have a 52 percent chance of being hit by one or more major storms with winds above 100 miles per hour. That's up from December's forecast of a 45 percent chance.
The years 1995-1999 were the most active five consecutive years of hurricanes on record in the Atlantic Basin, producing 65 named storms, 41 hurricanes and 20 major hurricanes. From 1990 to 1994 there were five major storms, Gray said.
"We're in this new era for major hurricanes," Gray said, adding that the premium conditions for hurricanes occur in decades-long cycles. "We had this lull between the mid 1960s and mid 1990s, and we think we turned the corner in 1995."
Gray, who has been studying hurricanes for more than 40 years, started issuing forecasts in 1984. Last year the National Hurricane Center joined him in making a prediction for the size and severity of the storm season, because federal officials believe there is no bigger natural disaster than a hurricane.
Of 1999's major hurricanes, Bret, Cindy, Floyd, Gert and Lenny were Category 4, which are characterized by top sustained winds of 131 to 155 mph, and Floyd was considered the most destructive in the United States, damaging or destroying 12,000 homes and causing an estimated $6 billion in damage in North Carolina alone.