Hurricane Forecasters Issue April Update for 2008 Season

April 10, 2008

A “well above-average” Atlantic hurricane season with eight hurricanes and 15 named storms entering the basin is predicted for 2008, according to forecasters at Colorado State University’s Department of Atmospheric Science.

“We have increased our seasonal forecast from our initial early December prediction. We anticipate an above-average probability of United States major hurricane landfall,” said Philip J. Klotzbach and William M. Gray in an April 9 report released by the forecasters.

The number of predicted named storms in 2008 has increased from 13 to 15 since CSU’s December report and the number of hurricanes predicted to enter the Atlantic basin this year has risen from seven to eight, according to the April announcement.

The CSU forecast is based on a new extended-range early April statistical prediction scheme that utilizes 58 years of past data. Information obtained through March 2008 indicates that the upcoming hurricane season will be much more active than the average 1950-2000 season.

The probability of U.S. major hurricane landfall is estimated to be about 135 percent of the long-period average. Klotzbach and Gray expect Atlantic basin Net Tropical Cyclone activity this year to be approximately 160 percent of the long-term average.

The methodology of this year’s extended-range forecast is based on a recently developed statistical technique built on 58 years (1950-2007) of data.

According to the Klotzbach and Gray analysis, the probability for at least one major hurricane (category 3, 4 or 5) making landfall anywhere on the U.S. coastline is 69 percent compared to an average probability of 52 percent in the last century.

The chances of a major hurricane hitting the East Coast including the Florida peninsula have increased from 31 percent last century to 45 percent for this year, the forecasters said. And for the Gulf Coast, from the Florida panhandle westward to Brownsville, Texas, the probability of a major hurricane strike is 44 percent, up from an average of 30 percent last century, according to Klotzbach and Gray.

Klotzbach and Gray said that while seasonal forecasts are based on statistical schemes, their “intrinsically probabilistic nature” dictates that they will fail in some years. Moreover, these forecasts do not specifically predict where within the Atlantic basin these storms will strike. The probability of landfall for any one location along the coast is very low and reflects the fact that, in any one season, most U.S. coastal areas will not feel the effects of a hurricane no matter how active the individual season is.

The forecasters admit that it is impossible to precisely predict a season’s hurricane activity in early April, and they added that the forecasts are issued to satisfy the curiosity of the general public and to bring attention to the hurricane problem.

“Our new early April statistical forecast methodology shows strong evidence over 58 past years that significant improvement over climatology can be attained,” Klotzbach and Gray said. “We would never issue a seasonal hurricane forecast unless we had a statistical model developed over a long hindcast period which showed significant skill over climatology.”

Source: Colorado State University

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