The last four months of hurricane season could be busy ones in the Atlantic Ocean, with government forecasters raising their expectations to an 85 percent chance of a normal or above-normal season.
The Atlantic could be in for three to six hurricanes, two or three of them major hurricanes, through November, according to an updated forecast the National Oceanic and Atmospheric Administration released Thursday. Major hurricanes rank 3, 4 or 5 on the Saffir-Simpson hurricane scale.
NOAA raised its predictions relative to its pre-season forecast made in May, now calling for 12 to 17 named storms instead of 9 to 15, and five to eight hurricanes instead of four to eight. There is a 70 percent chance of those predictions coming true, Gerry Bell, lead hurricane season forecaster for the Climate Prediction Center, said on a conference call Thursday morning.
The Atlantic has already seen six named storms, two of them Category 1 hurricanes -- Chris, which never made landfall, and Ernesto, which is drenching southern Mexico.
There are what Bell called "competing factors" influencing how the hurricane season plays out. On one hand, wind patterns are conducive to storm development and ocean temperatures are warm, Bell said. But, according to climate forecasters, El Nino is now likely to develop in August or September, inhibiting hurricane formation.
A high vertical wind shear, meaning large differences between wind speeds at varying elevations, makes it more difficult for tropical weather systems to develop rotation.
Even if El Nino develops soon, its impact on the Atlantic hurricane season could be far off. The phenomenon is associated with Pacific Ocean surface temperatures, so it can take weeks for its effects to reach the Atlantic, Bell said.
The looming El Nino made other forecasters' predictions lower than those of NOAA forecasters, though most have raised their expectations as the season wears on. The Tropical Meteorology Project at Colorado State University is predicting a slightly below-normal season, with five more hurricanes, two of them major hurricanes, according to a season update posted July 31. AccuWeather is meanwhile predicting three more hurricanes, two of them reaching major hurricane status.
A normal Atlantic hurricane season produces 12 named storms, six hurricanes, and three major hurricanes, according to NOAA.
National Weather Service Acting Director Laura Furgione encouraged residents along the Atlantic and Gulf of Mexico coasts to prepare for storms -- particularly the inland flooding brought on by storms like last year's Hurricane Irene. She encouraged people to visit www.ready.gov to ensure they have what they need to weather a storm.
"We have no control over these things like when or where a hurricane will strike," Furgione said. "We can have a lot of power over nature's ability ot impact our lives."
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