Atlantic basin tropical storm activity and U.S. landfall of tropical storms during the upcoming hurricane season are forecast to be about 35% above the 1950-2008 norm, according to London-based forecaster Tropical Storm Risk (TSR). TSR called for 4.8 named storms making U.S. landfall, including 2.1 hurricanes.

TSR’s April forecast update, compiled by Benfield University College London’s Hazard Research Center, calls for 15 named storms, including 7.8 hurricanes, 3.6 of them intense (Category Three or greater) forming in the Atlantic Basin between June 1 and Nov. 30. A total of 16 named storms, including eight hurricanes, five of them intense, formed during the 2008 season.

Slower-than-normal trade winds in the area where most Atlantic hurricanes develop was a key factor leading to the “active” forecast, TSR said.

TSR predicted a more intense hurricane season than Colorado State University (CSU) forecasters, who last week lowered their Atlantic hurricane season forecast to 12 named storms, with at least half of them likely to become hurricanes, two of them intense (see Daily GPI, April 8). The CSU team had previously estimated there would be 14 named storms during the 2009 season (see Daily GPI, Dec. 11, 2008). The CSU team lowered its hurricane forecast because it has seen anomalous cooling of sea surface temperatures in the tropical Atlantic over the past few months. Cooler waters are considered less conducive for an active Atlantic hurricane season.

The latest CSU forecast was similar to two recent forecasts by and WSI Corp.’s Chief Long Range Forecaster Joe Bastardi last month called for 13 named storms, including two intense hurricanes (see Daily GPI, March 19). WSI’s 2009 Atlantic forecast issued in December also predicted 13 named storms, three of them intense (see Daily GPI, Dec. 29, 2008). WSI plans to update its tropical season forecast on April 22.

According to the National Oceanic and Atmospheric Administration (NOAA), an average Atlantic hurricane season has 11 named storms, which includes two major hurricanes. NOAA said the Atlantic’s tropical storm development is increasing. Research indicates that the ocean has periods of 20-30 years when there are more storms than “normal.” The current cycle began in 1995, the agency noted.

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