A September to Remember

Thanks to Harvey, Irma, Jose and Maria, There's Never Been a Hurricane Season Like 2017

Though conditions were favorable to storm development all summer, September was the month everything changed.

By Pam Daniel June 27, 2018 Published in the July 2018 issue of Sarasota Magazine

Image: Shutterstock

“In 2017, September was the hurricane season,” says Longboat Key atmospheric scientist Bob Bunting. All summer, ocean waters were exceptionally warm—thermal maps show a sea of red off Florida and throughout the Caribbean—all the way down to 200 feet, providing a simmering cauldron of energy to fuel big storms. And there was another factor favorable to storm development: No winds were blowing to shear off the top of a developing hurricane. Yet there was little storm activity all summer long.

“Then, in September, Harvey formed,” says Bunting. “In 24 hours it went from a little tropical storm to an explosive major hurricane.” Soon after came Irma, Jose and Maria—“three mega-storms and three of them in the water at the same time!” he says. The ACE (accumulated cyclone energy) factor of those storms was off the charts, says Bunting; see below.


Normal ACE of an entire hurricane season


ACE of a hyperactive hurricane season


ACE of 2017 hurricane season

Harvey’s ACE: 11; Irma, 66; Jose, 42; Maria, 45

(Irma’s ACE alone met NOAA’s definition of an average full Atlantic hurricane season; Bunting compares the whirling energy of Irma to a “meat grinder.”)

A few other milestones from Bunting

Harvey was the first Category 4 hurricane to make landfall in Texas since Carla (1961) and in the United States since Charley (2004).

Harvey was the longest-lasting named storm on record after making landfall in Texas (117 hours). Prior record was Fern (1971)—54 hours.

Harvey produced 60.58 inches of rain in Nederland, Texas; the previous record was 48 inches for the continental U.S. from Tropical Storm Amelia in Texas.

Irma’s winds of 185 mph made it the strongest Atlantic storm on record; it spent 3.25 days as a Category 5, tying with the Cuba hurricane of 1932 for longest-lived Atlantic Category 5.

Maria had the lowest central pressure (which draws in warm, moist air) of any hurricane on record in the eastern Caribbean; it was the first Category 4 to make landfall in Puerto Rico since 1932 and the strongest to make landfall there since 1928.

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