The Colorado State University (CSU) hurricane forecast team predicts a slightly below-average 2009 Atlantic basin season based on a cooler-than-normal tropical Atlantic and the greater potential for a weak El Nino during the bulk of the hurricane season.
The team now anticipates 11 named storms forming in the Atlantic basin between June 1 and Nov. 30. Five of the storms are predicted to become hurricanes, and of those five, two are expected to develop into major hurricanes with sustained winds of 111 mph or greater.
The scientists reduced their forecast from April's prediction of 12 named storms, six hurricanes and two major hurricanes. Long-term averages are 9.6 named storms, 5.9 hurricanes and 2.3 major hurricanes/year.
Jim Rouiller, senior business meteorologist and tropical storm expert at Planalytics, agrees with the forecast. He says the major factors that lead to an active hurricane season are indicating a higher probability that the U.S. will experience a less active season than 2008.
Roullier says cooling sea surface temperatures, higher barometric pressure readings, increased wind shear because of El Nino that will cut the top off of developing storms and increased hot, dusty winds blowing off the Sahara desert into the Atlantic ocean all add up to fewer storms this hurricane season.
According to the CSU forecast team, "The probability of a major hurricane making landfall along the U.S. coastline is 48% compared with the last-century average of 52%." The hurricane forecast team also predicts a 28% chance that a major hurricane will make landfall on the U.S. East Coast, including the Florida Peninsula (the long-term average is 31%) and a 28% chance that a major hurricane will make landfall on the Gulf Coast from the Florida Panhandle west to Brownsville (the long-term average is 30%).
Probabilities of tropical storm-force, hurricane-force and major hurricane-force winds occurring at specific locations along the U.S. East and Gulf Coasts within a variety of time periods are posted on the forecast team's Landfall Probability website. The site provides U.S. landfall probabilities for 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine. Access the site.
The forecasters advise coastal residents not to change their hurricane preparedness measures because of a less active seasonal forecast since major hurricanes can devastate coastal communities in less active seasons. “Remember Andrew,” Roullier says. “Andrew was the only significant storm of that season. It only takes one.”