2024 has proven to be a historic hurricane season, with Hurricane Milton being the fifth strongest hurricane in the Atlantic and producing a record-breaking 126 tornado warnings for the state of Florida. Subsequently, Hurricane Helene made news around the world as the deadliest and costliest hurricane to hit the U.S. since Hurricane Katrina in 2005. Helene caused historic damage to parts of the southeastern U.S., especially western North Carolina, as news of the catastrophic flooding continues to spread around the globe. Experts and observers are wondering how Helene was able to cause such a high level of flooding so far from where it made landfall in Florida.
Helene made landfall as a category 4 hurricane just south of Perry in northwest Florida in what is called the “big bend,” the section of the coast where mainland Florida curves into the panhandle. The storm surge was estimated at 15 feet in this area. There were mandatory evacuations along this section of the Florida coast, and several preparations were taken beforehand as this area is prone to hurricanes. Less experienced areas, however, across the southeastern United States were not ready for what was to come in the following days. Recovery is currently expected to take months and possibly even years. The death toll currently sits at over 200, with hundreds still unaccounted for.
Georgia, South Carolina, North Carolina, and Tennessee were subjected to low category 1 and tropical storm force winds as Helene weakened traveling over land. These areas received heavy rains as Helene barreled towards Florida. As Helene passed over the Southern Appalachian region, it delivered an additional 40 trillion gallons of water to the area, with some counties receiving over 2 feet of rain.
Scientists are proposing that Helene was subjected to the “brown-ocean effect.” Normally, dry land deprives a tropical cyclone of energy and causes it to weaken rapidly. However, the waterlogged soils from the heavy rain experienced days before Helene, combined with the hot late-summer weather, provided fuel to the storm much like warm ocean water would. This caused Helene to weaken much more slowly and deliver the historic deluge.
The rains experienced before Helene contributed to the destruction by saturating the soil prior to the storm’s arrival, leading to runoff. The runoff caused rivers to swell over their banks, leading to flooding of adjacent areas. In low-lying towns like Asheville, which are surrounded by higher elevations, precipitation ran off the saturated mountainsides and pooled in these areas.
The increased frequency and intensity of hurricanes is a consequence of human-caused climate change. A warmer climate leads to warmer ocean temperatures, which rapidly strengthens storms. One study found that storms are now 25% more likely to reach major hurricane status than they were 40 years ago. Hurricane Milton’s explosive quick escalation was only surpassed by two other hurricanes, both of which occurred in the past two decades.
Storms like Helene and Milton are expected to become more common. Communities miles inland from the coast are being encouraged to prepare for the possibility of major flooding from tropical cyclones. This hurricane season has shown that new methods of warning residents, as well as clearly outlining the proper precautions that need to be taken, are urgently needed.
By Sarah Ortega