Forecasters have a higher confidence for an active season

The Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) issued its updated 2011 Atlantic hurricane season outlook today raising the number of expected named storms from its pre-season outlook issued in May. Forecasters also increased their confidence that 2011 will be an active Atlantic hurricane season. NOAA’s Climate Prediction Center, a division of the National Weather Service, updates its Atlantic hurricane season outlook every August.

“The atmosphere and Atlantic Ocean are primed for high hurricane activity during August through October,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at the Climate Prediction Center.  “Storms through October will form more frequently and become more intense than we’ve seen so far this season.”

Key climate factors predicted in May continue to support an active season. These include: the tropical multi-decadal signal, which since 1995 has brought favorable ocean and atmospheric conditions, leading to more active seasons; exceptionally warm Atlantic Ocean temperatures (the third warmest on record); and the possible redevelopment of La Niña.  Reduced vertical wind shear and lower air pressure across the tropical Atlantic also favor an active season.

Based on these conditions and on climate model forecasts, the confidence for an above-normal season has increased from 65 percent in May to 85 percent. Also, the expected number of named storms has increased from 12-18 in May to 14-19, and the expected number of hurricanes has increased from 6-10 in May to 7-10. Read NOAA's full release