Published: Wednesday, April 4, 2007
Storm forecasters call for jump in hurricanes
Unusually warm water in the Atlantic tropics is a major factor.
NEW ORLEANS The 2007 Atlantic hurricane season will likely be "very active" with 17 named storms, including nine hurricanes, five of them major, storm forecasters William Gray and Philip Klotzbach said Tuesday.
At the same time, they call for a 74 percent chance that a major hurricane, with sustained winds greater than 110 mph, will strike the U.S. coastline, which is considerably higher than the long-term average of 52 percent.
They also predict a 50 percent chance that a major hurricane will hit the U.S. East Coast, including the Florida peninsula, though the long-term average is 31 percent.
If the forecast holds true, it would be a substantial jump in activity over the relatively quiet 2006 season, which saw 10 named storms, including five hurricanes, and was only the 12th year since 1945 that the United States escaped a hurricane strike.
But 2007 shouldn't be as busy as the tumultuous 2004 and 2005 seasons, which combined, saw eight hurricanes slam Florida, the two forecasters based at Colorado State University said.
"The activity of these two years was unusual, but within the natural bounds of hurricane variation," Gray, who pioneered long-range seasonal forecasting 24 years ago, said in a prepared statement.
A normal season sees about 11 named storms, including six hurricanes, with two of those being intense.
The advance forecast, issued almost two months before the official June 1 start of the six-month season, is largely based on a faded El Nino, an atmospheric condition that inhibits storm formation and that helped subdue tropical activity last year, Klotzbach said.
"When you have El Nino conditions during the hurricane season, it increases vertical wind shear across the tropical Atlantic and typically results in a weaker tropical cyclone season," he said.
Also factored into their 2007 prediction: abnormally warm waters in the tropical region of the Atlantic, where hurricanes frequently are spawned. That is the result of a natural cycle that has created an era of heightened storm intensity that could last another 15 to 20 years, and not because of global warming, Gray contends.
"Although global surface temperatures have increased over the last century and over the last 30 years, there is no reliable data available to indicate increased hurricane frequency or intensity in any of the globe's seven tropical cyclone basins, except for the Atlantic over the past 12 years," Gray said.
In all, Gray and Klotzbach call for 2007's tropical activity to be 185 percent of average. By comparison, 2005 saw 275 percent of average.
In their initial forecast for 2007, Gray and Klotzbach called for 14 named storms, including seven hurricanes. Since then, government forecasters say La Niña, an atmospheric condition that promotes storm formation, appears to be emerging, although Gray's team made no mention of that in their forecast.
Gray over-estimated his initial forecast for 2006 because he admits he didn't see El Niño arising. Later this week, Gray and Klotzbach will be attending the National Hurricane Conference in New Orleans to further explain their forecast.