The 2011 Atlantic hurricane season, which officially begins in just two weeks, will be active but produce fewer tropical storms than previously expected, according to forecasters at MDA EarthSat Weather, who said warming waters in the Pacific Ocean will also keep a lid on summer temperatures.
A faster-than-expected transition to El Nino/Southern Oscillation-neutral conditions this spring suggests that the summer "will be approximately 14.5% cooler than last summer," said Travis Hartman, energy weather manager and meteorologist for MDA EarthSat.
"While the summer forecast for the nation as a whole now sits between the 10-year and 30-year normals, there will still likely be some events during the course of the season that will bring about significant cooling demands. The drought-stricken areas of the South seem most likely to see these heat events, but even areas along the eastern seaboard -- including the PJM region -- should expect some variability that could produce notable events."
Andover, MA-based WSI Corp. has said it expects temperatures through July to average cooler than normal across the northern United States, while above-normal temperatures will dominate the nation's southern tier (see Daily GPI, April 26).
Warming sea surface temperatures in the Pacific will also limit the number of tropical storms that form in the Atlantic Basin, Hartman said.
"The increased heat content in the Pacific, especially the East Pacific, will likely increase convective thunderstorm activity over that region, which would then increase the amount of wind shear over the tropical Atlantic. This in turn equates to lower activity expectations in the Atlantic, but not quite yet at the level where we would expect below-normal tropical activity."
MDA EarthSat said it expects 14 named storms, including seven hurricanes, five of them Category Three or greater, to form in the Atlantic this year. In its initial tropical forecast earlier this year, MDA EarthSat predicted 16 named storms and six hurricanes.
The revised outlook was generally in agreement with WSI's latest forecast, which calls for 15 named storms, including eight hurricanes, four of them intense (see Daily GPI, April 27), and remains 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). But despite being one of the busiest hurricane seasons in years, 2010 brought relatively little damage to the U.S. mainland and energy interests in the Gulf of Mexico. Short-term weather patterns, including the position of the jet stream and the tendency of last year's tropical storms to form in the extreme eastern Atlantic, helped to keep many of 2010's storms away from the United States, according to the National Oceanic and Atmospheric Association.
MDA EarthSat and WSI both believe there is a greater likelihood of hurricane landfall in the United States this year than there was in 2010.
"Last season saw plenty of events during the season, but as far as the energy industry was concerned it was a nonevent since there was a lack of any notable landfalls," Hartman said. "This year, however, while the activity numbers are expected to be lower year on year, various years in the analog set used to construct the forecast suggest more activity will be seen towards the U.S. coastline."
AccuWeather.com forecasters, who have also predicted a higher-than-normal number of tropical systems with more direct impacts on the U.S. than last year, have said any effects of hurricanes on the energy industry -- including spiking prices for gasoline -- aren't likely to last long.
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