By Kevin Gray
MIAMI (Reuters) - The 2011 Atlantic hurricane season will be active with the energy-rich U.S. Gulf Coast facing a significant threat of a hurricane landfall, a leading private weather forecaster predicted on Tuesday.
The forecast by Weather Services International follows one of the busiest seasons on record last year that saw intense levels of storm and hurricane activity but no direct hit on the U.S. coastline.
WSI slightly lowered its December forecast, calling for 15 named storms and eight hurricanes. Four are expected to grow into major hurricanes of Category 3 or higher on the five-step Saffir-Simpson intensity scale, it said.
"While we expect less overall activity this year, we do expect a much more impactful season along the U.S. coastline," WSI's chief meteorologist Todd Crawford said in a statement.
Other private forecasters have made similar predictions for the 2011 season set to begin June 1 and run through November 30.
A faster-than-expected weakening of the La Nina phenomena could also lower any favorable winds for storm development in the upcoming tropical season, Crawford said, explaining the forecast reduction.
The 2010 season spawned 19 named storms, tying for the third most active season with 1887 and 1995, according to the U.S. National Hurricane Center. Twelve storms strengthened into hurricanes last year, making it the second-highest season tied with the year 1969.
NO LANDFALLS SINCE 2008
The U.S. coastline has been spared a direct hit since 2008. Last year, Hurricane Earl, which grew into a Category 4 hurricane, came the closest by approaching to about 100 miles off North Carolina and southern New England in September.
"Our recent good fortune in avoiding landfalling hurricanes is not likely to last," Crawford said.
Projection models, he said, showed the western states on the U.S. coast of the Gulf of Mexico, where major oil and gas installations are located, facing "sharply increased" chances of a landfall this year.
Crawford predicted two or three hurricanes could come ashore.
"The U.S. has not had a three-year stretch without a hurricane landfall since the 1860s," he added.
A change in weather conditions is also increasing chances of an hurricane making impact on the U.S. coastline, according to Crawford.
Pockets of low pressure in the Atlantic helped to shield the U.S. East Coast from direct hits last year, but are not expected to be present later this summer when storm activity intensifies, he said.
Warmer sea surface temperatures in the Gulf of Mexico and the Caribbean may also help storms develop more easily there instead of farther out in the Atlantic, Crawford added.
"Storms developing in the Gulf and the Caribbean are a much greater threat to make landfall along the U.S. coast than those that develop off the coast of Africa," he said.
WSI said its forecast numbers were similar to the 2008 season when Hurricanes Dolly, Gustav and Ike impacted Louisiana and Texas.
(Editing by Tom Brown and Lisa Shumaker)