2013 Atlantic hurricane season among least active since 1950

This year’s Atlantic hurricane season, which ends Saturday, has had the fewest number of hurricanes since 1982, the National Oceanic and Atmospheric Administration in the United States said this week.

That’s mainly because of “persistent, unfavorable atmospheric conditions over the Gulf of Mexico, Caribbean Sea, and tropical Atlantic Ocean,” the organization said.

Overall, 2013 is set to rank as the sixth least active Atlantic hurricane season since 1950, in terms of collective strength and duration of named storms and hurricanes, according to the NOAA.

This season was also the third below-normal season in the last 19 years, since 1995, when the current high-activity era for Atlantic hurricanes began, the NOAA said.

“A combination of conditions acted to offset several climate patterns that historically have produced active hurricane seasons,” Gerry Bell, Ph.D. and lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, a division of the National Weather Service, noted in a statement. “As a result, we did not see the large numbers of hurricanes that typically accompany these climate patterns.”

The season had 13 named storms, two of which (Ingrid and Humberto) became hurricanes. Neither of those storms became major hurricanes (Category 3 or above). The average number of named storms in 12, according to the NOAA, but the number of hurricanes and major hurricanes this year was below the averages of six and three, respectively.

The only named storm to make landfall in the U.S. was tropical storm Andrea, the first of the season, which brought tornadoes, heavy rain, and minor flooding to portions of Florida, eastern Georgia and eastern South Carolina, causing one fatality, according to the NOAA.

However, Mexico was hit by eight storms this year, including three from the Atlantic basin and five from the eastern North Pacific, the NOAA noted. Of those, five were tropical storms and three were hurricanes.

“This unexpectedly low activity is linked to an unpredictable atmospheric pattern that prevented the growth of storms by producing exceptionally dry, sinking air and strong vertical wind shear in much of the main hurricane formation region, which spans the tropical Atlantic Ocean and Caribbean Sea,” Bell said. “Also detrimental to some tropical cyclones this year were several strong outbreaks of dry and stable air that originated over Africa.”

The NOAA and the U.S. Air Force Reserve flew 45 hurricane hunter aircraft reconnaissance missions over the Atlantic basin this season, totaling 435 hours–the fewest number of flight hours since at least 1966, the organization added.

Image: GOES East satellite tracks Subtropical Storm Melissa, the last storm of the season. (Credit: NOAA)