With the slow start to the 2010 Atlantic hurricane season forcing some forecasting services to recalibrate their expectations going forward, WSI Corp. on Tuesday said it is lowering its expectations from 20 named storms to 19, while keeping its prediction that there will be 11 hurricanes and five intense hurricanes, signified as Category 3 or greater.

Prior to the reduction, WSI had bumped its expectations higher no less than three times since its original January forecast. In its original forecast, WSI called for 13 named storms, including seven hurricanes, with three of them intense, (see Daily GPI, Jan. 27). In April WSI increased its forecast to include 16 named storms, including nine hurricanes, five of them intense (see Daily GPI, April 21) and in May it increased its forecast to 18 named storms, including 10 hurricanes, five of them intense (see Daily GPI, May 26). In June the company increased its outlook to 20, 11 and five, respectively (see Daily GPI, June 23).

In acknowledging the reduced forecast, WSI warned that the new 2010 forecast numbers are still well above the long-term (1950-2009) averages of 10 named storms, six hurricanes, and two intense hurricanes and slightly above the averages from the more active recent 15-year period (1995-2009) of 14/eight/four.

WSI said its hurricane landfall forecasting model (developed in collaboration with reinsurance intermediary Guy Carpenter) continues to suggest that the coastal region from the Outer Banks of North Carolina northward to Maine is twice as likely as normal to experience a hurricane this year. The forecasting service noted that its model suggests the threat to the Northeast coast this season is on par with that in Florida and the Gulf coastal states.

“Record warm tropical Atlantic ocean temperatures and an enabling wind shear environment should result in a very active tropical season this year,” said WSI Chief Meteorologist Todd Crawford. “The El Nino event has vanished completely, resulting in a decrease in central tropical Pacific convection and a concomitant decrease in the vertical wind shear that typically acts as a detriment to tropical Atlantic development. More importantly, however, eastern and central tropical Atlantic sea surface temperatures are currently at record warm levels for July, even warmer than the freakishly active season of 2005. Water temperatures are already at levels more typical of late August.

“While all of the primary drivers are strongly enabling for tropical activity, we have had a slow start relative to other very active seasons. Further, a pocket of very dry air in the tropical Atlantic will likely limit development in the near term. Because of these factors, we have decreased our forecast total number of named storms from 20 to 19. We still expect an extremely active August-October period.”

The next update on the 2010 tropical season will be released on Aug. 25.

The National Oceanic and Atmospheric Association said last week it still expects the 2010 Atlantic season to be “active to extremely active,” with 14-23 named storms, including eight to 14 hurricanes, and three to seven of them being intense (see Daily GPI, July 16).

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