The near-record pace of the 2011 Atlantic hurricane season already has the 15th named storm of the year charging across the Atlantic Ocean, and another six named storms are likely to form before the season's official end on Nov. 30, according to forecasters at Andover, MA-based WSI. Corp.
In its final hurricane update of the year, WSI increased its forecast to a total of 21 named storms, including seven hurricanes, four of them intense (Category Three or greater). In its previous forecast, WSI said it expected 18 named storms, including eight hurricanes, four of them intense, to form this year (see Daily GPI, Aug. 25). The long-term (1950-2010) average for the Atlantic Basin is 12 named storms, including seven hurricanes, three of them intense.
The fact that only three of the season's 15 named storms to date have reached hurricane status "is quite unusual and is likely a reflection of the reduced instability over the Atlantic sector so far this season," said WSI Chief Meteorologist Todd Crawford.
In previous forecasts WSI had said the Gulf of Mexico (GOM) would be under the greatest threat of hurricane landfall this season, but changing conditions have the forecaster rethinking that prediction.
"Irene was the first landfalling hurricane in the U.S. since Ike in 2008, and all three hurricanes (Irene, Katia, and Maria) so far have recurved before threatening the Gulf States," Crawford said. "This reflects the continued dominance of the eastern U.S. and western Atlantic troughing that has generally been in place since 2009. The tropical storms (Don, Lee, Nate) that have threatened the Gulf so far have generally underperformed. This is due, in part, to the unseasonably dry air associated with the southern Plains drought. While the near-term pattern may favor more southern tracks and a higher Gulf threat, the expected return of eastern U.S. troughing in late September suggests that our original forecast for enhanced Gulf landfall chances may be in doubt."
On Wednesday the National Hurricane Center (NHC) said Tropical Storm Ophelia, the 15th named storm of the year, was becoming stronger in the central Atlantic Ocean about 1,245 miles east of the Leeward Islands. Ophelia was expected to move west through Thursday with a gradual turn toward the west-northwest on Friday, according to NHC. The storm's maximum sustained winds had increased to near 60 mph on Wednesday, but were expected to weaken through Friday, NHC said.
While the number of tropical storms this year has been relatively high, they have presented only sporadic danger to GOM energy interests. Most have followed trajectories similar to that of Hurricane Maria, which last week swirled harmlessly well offshore the East Coast before dissipating in the North Atlantic.
But four oil workers died after they and six others were forced to abandon a liftboat in the southern GOM during Tropical Storm Nate earlier this month (see Daily GPI, Sept. 19; Sept. 12a). Tropical Storm Lee forced temporary shut-ins and the evacuation of production platforms and mobile drilling rigs in the GOM (see Daily GPI, Sept. 9), as did Hurricane Don, though to a lesser extent (see Daily GPI, Aug. 2).
Hurricane Irene steered clear of the GOM but turned out the lights on millions of East Coast residents and in doing so cut demand for natural gas by about 2.8 Bcf (see Daily GPI, Aug. 30).
A La Nina weather phenomenon, which contributed to extreme weather around the globe in the first six months of this year, has reemerged in the tropical Pacific Ocean and is forecast to gradually strengthen and continue into winter, according to the National Oceanic Atmospheric Administration (NOAA) (see Daily GPI, Sept. 12b). Seasonal hurricane forecasters factored the potential return of La Nina into NOAA's updated 2011 Atlantic hurricane season outlook, issued in August, which called for an active hurricane season (see Daily GPI, Aug. 5).
AccuWeather.com forecasters last month predicted a ramping up of tropical activity (see Daily GPI, Aug. 12) and WeatherBELL Analytics chief meteorologist Joe Bastardi in August said he expected tropical storm activity in the Atlantic Basin to increase through this month (see Daily GPI, Aug. 17). A series of tropical forecasters, including Colorado State University (see Daily GPI, June 2) and MDA EarthSat (see Daily GPI, May 18) have predicted above-average tropical storm activity in the Atlantic Basin.
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