The 2011 Atlantic hurricane season may not be as active as previously predicted, producing only as many tropical storms as the 1995-2010 average (15 named storms, including eight hurricanes, four of them Category Three or greater), but the United States can expect two or three hurricanes to make landfall this year, forecasters at WSI Corp. said Tuesday.

The WSI forecast numbers remain above the longer-term 1950-2010 average of 12 named storms, including seven hurricanes, three of them intense. A total of 19 named storms formed in 2010, with 12 of them becoming hurricanes, including five intense hurricanes (see Daily GPI, Dec. 1, 2010).

In its initial forecast for the 2011 Atlantic hurricane season, which officially begins June 1, WSI called for 17 named storms, including nine hurricanes, five of them intense, to form in the Atlantic basin this year (see Daily GPI, Dec. 9, 2010).

“We have reduced our forecast numbers to ‘active-normal’ levels since the recent North Atlantic weather pattern has resulted in a cooling of the tropical Atlantic sea surface temperatures,” said WSI Chief Meteorologist Todd Crawford. In addition, a faster than expected weakening of the current La Nina event — a cooling of ocean surface temperatures off the western coast of South America — reduces the possibility of a favorable wind shear environment during the upcoming tropical season, Crawford said.

However, while the number of tropical storms might not exceed the short-term average, the upcoming hurricane season is likely to have more of an impact on the U.S. coastline, which was spared major storm damage in 2010.

“The U.S. has been spared from any landfalling hurricanes since 2008, and the hurricane drought in 2009 and 2010 is relatively rare in the historical record. In fact, the U.S. has not had a three-year stretch without a hurricane landfall since the 1860s. Further, 80% of all years in the historical dataset have had at least one hurricane landfall in the U.S. Our recent good fortune in avoiding landfalling hurricanes is not likely to last.”

The Gulf Coast is “under a significant threat for hurricane landfall in the upcoming season,” according to Crawford. A persistent western Atlantic trough that protected the East Coast from direct hits in 2010 isn’t expected to be in place during peak hurricane months this year, and warmer sea surface temperatures in the Gulf of Mexico and Caribbean Sea should produce more tropical storms there, he said. WSI forecasters expect two or three landfalling hurricanes in 2011.

“This is not particularly unusual, since historically 43% of years have had multiple hurricane landfalls,” Crawford said. “The forecast numbers from our model are quite similar to those prior to the 2008 season, when Hurricanes Dolly, Gustav and Ike impacted Louisiana and Texas.” forecasters, who have predicted a higher-than-normal number of tropical systems with more direct impacts on the U.S. than last year, on Monday said any effects of hurricanes on the energy industry — including spiking prices for gasoline — aren’t likely to last long (see Daily GPI, April 26).

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