Increased likelihood of below-normal Atlantic hurricane season

Updated outlook calls for 90 percent probability of below-normal season

August 6, 2015

2015 Atlantic Hurricane Season Outlook. (Credit: NOAA)

(Credit: NOAA)

The NOAA Climate Prediction Center’s updated 2015 Atlantic Hurricane Season Outlook calls for a 90 percent chance of a below-normal hurricane season. A below-normal season is now even more likely than predicted in May, when the likelihood of a below-normal season was 70 percent.

“Tropical storms and hurricanes can and do strike the United States, even in below-normal seasons and during El Niño events,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with NOAA’s Climate Prediction Center. “Regardless of our call for below-normal storm activity, people along the Atlantic and Gulf coasts should remain prepared and vigilant, especially now that the peak months of the hurricane season have started.”

Two tropical storms already have struck the United States this year. Ana made landfall in South Carolina in May, and Bill made landfall in Texas in June.

The 90 percent probability of a below-normal season is the highest confidence level given by NOAA since seasonal hurricane outlooks began in 1998.

Satellite image of Subtropical Storm Ana forming off the East Coast. This image was taken by GOES East at 1245Z on May 8, 2015. (Credit: NOAA)

Satellite image of Subtropical Storm Ana forming off the East Coast. This image was taken by GOES East on May 8, 2015. (Credit: NOAA)

The updated outlook also lowers the overall expected storm activity this season. The outlook now includes a 70 percent chance of 6-10 named storms (from 6-11 in the initial May Outlook), of which 1-4 will become hurricanes (from 3-6 in May), and 0-1 will become major hurricanes (from 0-2 in May). These ranges — which include the three named storms to-date (Ana, Bill, and Claudette) — are centered well below the seasonal averages of 12 named storms, 6 hurricanes and three major hurricanes.

Forecasters attribute the high likelihood of a below-normal season to three primary factors:

 The Atlantic hurricane season runs from June 1 through November 30.

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