When Hurricane Helene made landfall on Florida’s Gulf Coast on September 26, 2024, it unleashed severe storm surges and widespread damage, while also generating significant ripples in the upper atmosphere. NASA’s Atmospheric Waves Experiment (AWE), stationed on the International Space Station, detected these massive atmospheric disturbances, known as gravity waves, around 55 miles above the Earth’s surface as the storm neared land. AWE’s observation of these atmospheric changes caused by terrestrial weather provides valuable insights into how such waves impact satellites and other remote sensing technologies.
Helene was a Category 4 hurricane with 140 mph sustained winds at its peak. Its hurricane-force winds extended to 60 miles from its center, while its tropical storm-force winds reached 345 miles. By the time the storm had moved inland, it was weakening to a tropical depression but still packing heavy rain and wind.
The hurricane’s colossal size was important in generating a destructive storm surge. The larger the storm, the more force it exerts in a broader ocean area and for extended periods. This translates into a higher storm surge that can overwhelm coastal areas with seawater several feet above average ocean height.
Another way a hurricane’s size matters is its ability to generate far-reaching tornadoes. The NHC warned of this when describing Helene’s impact on the coast and inland as it churned toward North Carolina. A large hurricane can create hundreds of tornadoes that destroy buildings and down power lines with a finger twist.
Aside from the tornadoes, Helene’s massive size caused severe flooding as it pushed through the Blue Ridge Mountains. The rainfall from the storm triggered mudslides, river flooding, and debris flows that caused significant problems in small mountain towns that weren’t directly on Helene’s path.
As the storm moved on, it deposited a thick layer of suspended sediment over much of the North Carolina coastline. As seen in this composite image taken by the Ocean Color Instrument on NASA’s Earth Observatory, swirls of color can be spotted along the coast even after the storm. The images remind us that hurricane damage can’t be judged by its Saffir-Simpson rating, which is based solely on wind intensity.