(USA TODAY) -- All of the forecasts are in, and with the heart of the hurricaneseason just weeks away, an unusually busy year still looks likely.
Thefinal "preseason" forecast from top experts at Colorado StateUniversity, released Friday morning, again calls for an "above-average2013 Atlantic basin hurricane season."
A total of 18 namedtropical storms are forecast to form, of which eight should behurricanes. This is a slight reduction from Colorado State's previousforecasts, which called for nine hurricanes.
A typical year, basedon weather records that go back to 1950, has 12 tropical storms, ofwhich seven are hurricanes. A tropical storm has sustained winds of 39mph; it becomes a hurricane when its winds reach 74 mph.
TheAtlantic hurricane season started June 1 and lasts until Nov. 30. So farthis year, four tropical storms have formed in the Atlantic, but nohurricanes, according to the National Hurricane Center. August andSeptember are the two most active months for hurricanes in the Atlantic.
The forecast does not include hurricanes that form in the eastern Pacific basin, which seldom affect the USA.
Theprediction was released by meteorologists Philip Klotzbach and WilliamGray at Colorado State's Tropical Meteorology Project.
Why the drop in the number of predicted hurricanes? "While thetropical Atlantic remains warmer than normal, it has cooled somewhat inthe eastern portion of the basin," Klotzbach said. Warm water providesthe fuel that helps a hurricane form.
Nevertheless, an activeseason still looks probable: "It appears that the chances of an El Niñoevent this summer and fall are unlikely," he says."Typically, El Niño isassociated with stronger vertical shear across the tropical Atlantic,creating conditions less conducive for storm formation."
ColoradoState was the first organization to issue seasonal hurricane forecasts,and is now in its 30th year of issuing these forecasts.
TheColorado State team's seasonal forecasts tend to be conservative: Since2000, the team has under-forecast the number of named tropical stormsand hurricanes seven times, over-forecast three times and been almostright - within two storms - three times, a USA TODAY analysis shows.