(image credit: Flickr)
Something’s shifted. And it’s not just the climate.
Even before being named a tropical storm, I knew that what would become Mean Helene was set on a mission to be yet another multibillion-dollar disaster. I knew that it would undergo rapid intensification and become a catastrophic hurricane. And I knew that a calamitous rainfall event would unfold in the Southeast many hours after landfall.
So, I did what I’ve done during my entire 40 year career—I tried to warn people. Except that the warning was not well received by everyone. A person accused me of being a “climate militant,” a suggestion that I’m embellishing extreme weather threats to drive an agenda. Another simply said that my predictions were “an exaggeration.”
But it wasn’t an exaggeration.
The storm surge from Helene was widespread and up to 15 feet (4.5 meters) deep. The windstorm sliced through the Southeast with gusts up to 100 miles per hour (160 km/hr). And the rains were, as I predicted, “biblical.”
Helene became a major hurricane on September 26th amid a rapid intensification (RI) cycle in which it attained 55 mph (~90 km/hr) greater windspeeds in a span of 24-hours—just short of the “extreme” RI threshold of 58 mph (~95 km/hr) in 24 hours. It was the second time since it formed that maximum sustained windspeeds had increased by at least 35 miles per hour (~55 km/hr) in a day.
As a result, Helene went from an 80-mph (130 km/hr) low-end Category 1 hurricane one day to a 140 mph (225 km/hr) Category 4 cyclone the next. According to the Saffir-Simpson Hurricane Wind Scale, Category 1 hurricane damage would be expected to be “minimal,” while Category 4 hurricane damage would be “devastating.”
Helene was the second major hurricane (Cat 3 or higher) of the 2024 season. Record-setting Hurricane Beryl preceded it as the earliest-forming Category 5 hurricane in the Atlantic basin’s history. Beryl became a major hurricane in the month of June east of the Lesser Antilles, the first time that’s ever happened during the first month of hurricane season since recordkeeping began in 1851.
While Beryl weakened before reaching the United States as a Category 1 hurricane, Helene intensified into a major hurricane and continued strengthening right up to landfall. That now puts 2020-2024 into the record books, tying the mark for the longest consecutive number of years (five) in which a major hurricane has made landfall in the United States.
Hurricane Helene’s wind field was about as large as they come. The diameter of sustained tropical storm force winds reached over 450 miles (725 kilometers). Based on historical statistics of tropical cyclone size, that put Helene in the 90th percentile. Miami, never closer than 300 miles (485 km) from Helene’s center, experienced a wind gust of 72 mph (116 km/hr). Hurricane force winds also extended out an unusually far distance of 60 miles (97 km) from the eye.
Read the complete analysis on the Bulletin of the Atomic Scientist
