Conditions in the Atlantic Ocean have grown more favorable for hurricanes in recent months, so forecasters at Colorado State University have boosted -- by two -- the number of storms they're expecting during the 2008 season, which opens June 1.
The combination of warmer sea-surface temperatures -- the "fuel" for storm development -- and more favorable sea-level winds should make this "a very active season," according to CSU's Phil Klotzbach and William Gray.
Hurricane activity from June through November will likely be "well above average," they said.
There's a 45 percent chance that a major storm -- with sustained winds of 111 mph or higher -- will make landfall somewhere along the East Coast or in Florida. The average for the past century is 31 percent.
Klotzbach and Gray are predicting 15 named storms in all, including eight hurricanes and three storms that reach "major" status, with Category 3 winds of 111 mph or higher.
Such storms, while comparatively rare, cause 80 to 85 percent of all hurricane storm damage. The probability that a Category 3 storm will make landfall on U.S. shores this year is about 135 percent of the average from 1950 through 2000, the forecasters said.
If they're right, the 2008 season will see the same number of named storms as last year, but two more storms would become hurricanes than last year and two more would reach Category 3 strength.
The CSU team delivered its annual April forecast yesterday at the 12th Annual Bahamas Weather Conference, on Grand Bahama Island.
Forecasters at the National Oceanic and Atmospheric Administration's Center for Climate Prediction will issue their 2008 hurricane forecast in May.
But government forecasters are expected to play down their own storm counts this year.
Bill Read, the new director of the National Hurricane Center, said last week that he wants the official forecasts to present predictions as being "above average, at average or below average," rather than placing emphasis on any specific storm counts, said NHC spokesman Dennis Feltgen.
The worry, he said, is that residents will drop their guard if the forecast calls for only a handful of storms in a coming season.
In 1992, for example, forecasters called for just seven named storms, only one of them a hurricane. But the first storm of the year was Hurricane Andrew, a Category 5 monster that devastated South Florida.
"As a property owner, the seasonal outlook makes no difference in your preparation plans," Feltgen said. Even if there is just one storm, "if it hits you, it's a bad year."
Forecasters have had a tough time with their hurricane predictions in recent years. In last year's April forecast, Klotzbach and Gray correctly predicted an "active" season. But their forecast of 17 named storms, including nine hurricanes and three "major" storms, was too high.
By the season's end, there had been 15 named storms, with six making it to hurricane strength. Only two became major storms, although both of those -- Dean and Felix -- made landfall as fearsome Category 5 hurricanes, killing more than 160 people in the Caribbean, Mexico and Central America.
Forecasters overestimated the storm activity in 2006 by even more. And they badly underestimated the ferocious pace of storms in 2005.
The 2005 season spawned 27 named storms and 15 hurricanes -- twice what Gray and Klotzbach had predicted in April. The storms included Katrina and Rita, which devastated New Orleans and other Gulf Coast communities from Texas to Alabama.
Forecasters say the long-term, natural cycles in air pressure and sea-surface temperatures in the Atlantic, which became more favorable for storms beginning in 1995, will continue to bias the system in favor of busier-than-average hurricane seasons for 15 to 20 years to come.
"We don't attribute this to anything humans are doing," Gray said. "These are natural" cycles.
Klotzbach and Gray said that while their old forecast models had done well prior to 1994, they've been less reliable since then. The forecasters blamed a "discontinuation" of statistical links between West African rainfall and other atmospheric factors.
"We do not yet have a good explanation for as to why these relationships failed," they said.
This year they've rolled out another scheme based on Atlantic sea-surface temperatures and atmospheric pressure gradients over the ocean. Applied to past seasons, it predicted better than the April forecasts in 11 of the 13 years studied.
This year's CSU forecast also uses an "analog" technique, which looks for years with comparable ocean and atmosphere conditions, and notes how those hurricane seasons turned out.
The scientists found four comparable years -- 1950, 1989, 1999 and 2000. "All four of those years had well above-average hurricane activity," Klotzbach said.
Here are the hurricane names for the 2008 Atlantic season.
[Source: National Hurricane Center