The 2011 Atlantic hurricane season during its first nine weeks has thrown little tropical activity at the U.S. mainland and energy interests in the Gulf of Mexico, but it has produced five named storms, and the National Oceanic and Atmospheric Association (NOAA) expects as many as 14 more named storms to form this year.
"The atmosphere and Atlantic Ocean are primed for high hurricane activity during August through October," said Gerry Bell, lead seasonal hurricane forecaster at the NOAA Climate Prediction Center. "Storms through October will form more frequently and become more intense than we've seen so far this season."
In an updated forecast released Thursday, NOAA said the Atlantic basin is likely to produce a total of 14-19 named storms, including seven to 10 hurricanes, three to five of them Category 3 or greater. In a forecast released prior to the June 1 opening of the 2011 hurricane season, NOAA had predicted 12-18 named storms, including six to 10 hurricanes, three to six of them intense (Daily GPI, May 20).
Key climate indicators, including the tropical multi-decadal signal, exceptionally warm Atlantic Ocean temperatures and the possible redevelopment of La Nina event in the Pacific Ocean continue to support an active season this year, NOAA said. Reduced vertical wind shear and lower air pressure across the tropical Atlantic also favor an active season, prompting NOAA to increase its confidence in an above-normal season to 85% compared with 65% in May.
The consensus forecast this year continues to be for an above-average hurricane season. WSI Corp. recently said it expects a total of 15 named storms, including eight hurricanes, four of them Category 3 or greater -- the same as the 1995-2010 average -- to form this year (see Daily GPI, July 27). Forecasters at Colorado State University have said they expect to see 16 named storms form in the Atlantic Basin, with nine turning into hurricanes, five of them intense (see Daily GPI, June 2). AccuWeather.com (see Daily GPI, April 26; April 1) and MDA EarthSat have also forecast above-average numbers of named storms and hurricanes.
The Atlantic basin has produced five tropical storms so far this season: Arlene, Bret, Cindy, Don and Emily, which on Thursday afternoon was losing strength as it interacted with the mountains of Hispaniola. Maximum sustained winds had decreased to about 40 mph and Emily was expected to further weaken and dissipate by Friday morning, according to the National Hurricane Center.
A total of 19 named storms formed in 2010, with 12 of them becoming hurricanes, including five intense hurricanes. The long-term (1950-2009) averages for the Atlantic hurricane season are 10 named storms, six hurricanes and two intense hurricanes; the 1995-2009 averages are 14, eight and four, respectively.
The hurricane season officially ends Nov. 30.
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