NOAA Lowers Hurricane Season Outlook
August 2009 - Emergency Preparedness
As the calming effects of El Niño continue to develop, NOAA now expects a near- to below-normal Atlantic hurricane season, according to its August Atlantic hurricane season outlook.
NOAA’s Climate Prediction Center, a division of the National Weather Service, now predicts a 50 percent probability of a near-normal season, a 40 percent probability of a below-normal season, and a 10 percent probability of an above-normal season.
Forecasters say there is a 70 percent chance of seven to 11 named storms, of which three to six could become hurricanes, including one to two major hurricanes (category 3, 4 or 5).
During an average season, there are 11 named storms with winds of at least 39 mph, of which six become hurricanes with winds of 74 mph or greater and two of those become major hurricanes with winds of 111 mph or higher.
In recent weeks, forecasts for the return of El Niño – warmer than normal waters along the equatorial central and eastern Pacific Ocean – have come to fruition.
“El Niño produces stronger upper-level westerly winds over the Caribbean Sea and tropical Atlantic Ocean, which help to reduce hurricane activity by blowing away the tops of growing thunderstorm clouds that would normally lead to tropical storms,” says Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center.
The calm start to this hurricane season is not a reliable indicator of the overall activity for the entire season. The 1992 Atlantic hurricane season, for example, had a below-normal number of named storms and hurricanes. The first storm did not form until late August, when Hurricane Andrew hit southern Florida as a destructive Category 5 storm.