April 7, 2010

Above-Average Hurricane Season Predicted

Colorado State University's hurricane forecast team is predicting an above-average season for the Atlantic basin in 2010, which includes all tropical storms and hurricanes in the Caribbean Sea and Gulf of Mexico.

The forecast calls for 15 named tropical storms, of which eight will become hurricanes. A tropical storm becomes a hurricane when its sustained wind speeds surpass 74 mph. Of those eight, four are expected to develop into major hurricanes (Category 3, 4 or 5) with maximum wind speeds of 111 mph or greater. Looking at averages that go back to 1950, a typical Atlantic hurricane season sees 10 named storms — six of them hurricanes, with two major. "We expect current moderate El Nino conditions to transition to neutral conditions by this year's hurricane season," says Phil Klotzbach, lead forecaster on the Colorado State hurricane forecast team. "The dissipating El Nino, along with the expected anomalously warm Atlantic ocean sea-surface temperatures, will lead to favorable dynamic and thermodynamic conditions for hurricane formation and intensification."

Colorado State's Tropical Meteorology Project is the nation's longest-running and most well-known forecast team. Begun by William Gray in 1984, these seasonal forecasts are used by insurance companies, emergency managers and the media to prepare Americans for the season's likely hurricane threat. "Based on our latest forecast, the probability of a major hurricane making landfall along the U.S. coastline is 69% compared with the last-century average of 52%," Gray says. "While patterns may change before the start of hurricane season, we believe current conditions warrant concern for an above-average season."

Last month, private forecasting firm AccuWeather predicted that 16 to 18 tropical storms and hurricanes would form in the Atlantic hurricane basin, of which seven will make landfall on U.S. shores. The federal National Oceanographic and Atmospheric Administration is scheduled to release its hurricane forecast on May 20. Contrary to popular belief, hurricane forecasters don't "always" predict an above-average season that then doesn't come to pass. In fact, since 2000, the opposite is true: In the past decade, CSU's April forecasts have been wrong more than they've been right, but primarily because they've underestimated the threat.

In a USA TODAY analysis of the team's forecast data since 2000, CSU has under-forecast the number of named tropical storms and hurricanes four times, over-forecast the number three times, and been almost right (within two storms) on three occasions. In 2009, the CSU team's April prediction of a near-average season was slightly over-forecast. They predicted that 12 named storms would form, of which five would become hurricanes. In reality, nine named storms formed, of which three were hurricanes.
The hurricane season runs from June 1 to Nov. 30. The first named storm will be Alex, followed by Bonnie and Colin.
By Doyle Rice / USA Today

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