Northern Florida, coastal regions of Georgia and South Carolina, and parts of North Carolina are bracing for heavy rain and catastrophic flooding this week as the Debby Storm System moves up and east.
Debby arrived on the mainland as a Category 1 hurricane off the coast of Big Bend, Florida, on Monday morning, first hitting the small community of Steinhatchee. It damaged homes and businesses, caused increased flooding, caused power outages across the state and in Georgia, and led to several deaths. Debby was downgraded to a tropical storm at noon Monday.
But experts say the worst is yet to come, as the storm system is expected to stop in the Southeast.
How much rain is expected?
Forecasters say the system could hit the Southeast with widespread areas of up to 20 inches (51 centimeters) of rain and some totaling up to 30 inches (76 centimeters).
It would be record rainfall, breaking the record for a tropical system in 2018’s Hurricane Florence. More than 20 inches of rain was recorded in South Carolina after the storm made landfall in the Carolinas.
Although Debby was classified as a Category 1, “she really deserves a Category 3 or 4 rating if you want to talk about the impacts of rainfall,” said Jeff Masters, founder of Weather Underground, now with Yale Climate Connections. “This will cause a lot of damage.”
What areas are at risk?
North Florida, as well as low-lying areas including Savannah, Georgia, Hilton Head Island and Charleston, South Carolina, are expected to experience the most severe flooding. North Carolina could also be affected.
Officials in Savannah warned the area could receive a month’s worth of rain in four days if the system stops. There were also concerns about flooding on Tybee Island, Georgia’s largest public beach, 18 miles (28.97 kilometers) east of Savannah. In addition to any torrential rain Debby brings, the island could get even wetter with a storm surge of 2 to 4 feet, according to the National Hurricane Center.
“We don’t know how much rain will fall. But we have to prepare for the worst,” said Hilton Head Island Mayor Alan Perry in a video posted to Facebook. “If that happens, we will see an event we have never seen before on Hilton Head.”
Meanwhile, Charleston County Interim Emergency Director Ben Webster called Debby a “historic and potentially unprecedented event” three times in a 90-second briefing Monday morning.
Few places in South Carolina are as susceptible to flooding as Charleston. Much of the city and surrounding areas founded in 1670 were built on land created with fill earth and other debris. Rising sea levels cause a series of minor floods even without a storm, and like many coastal cities, Charleston cannot drain well.
The city is not expecting major flooding from the ocean, but the storm is still dangerous. Heavy rains could return to the city, also causing flooding.
What is causing this storm?
Some hurricanes make landfall and move quickly, experts say, while others slow down substantially.
“What actually happened, and the reason the storm stalled, was because basically there are areas of high pressure to the west and northeast of the storm, and that kind of trapped the storm,” said Phil Klotzbach, senior research scientist at State University from Colorado. Department of Atmospheric Sciences. “With a hurricane you always have wind problems, but when you have a storm moving at 3 to 5 miles per hour, it’s going to pass over any specific location for a long period of time, so flash flooding and huge rainfall totals are will be very likely.”
Experts say warming of the atmosphere plays a role in the severity of storms like Debby.
Warming water in the northeastern Gulf of Mexico is increasing Hurricane Debby’s heavy rainfall as more moisture evaporates from the waters, Masters said. Some research says climate change could impact the progress of hurricanes, he added, making them slower.
“It’s something we’ve been seeing more of lately,” Masters said.
How long could this last?
The worst of the rain is expected during the first half of the week but could last until Saturday, forecasters said.
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St. John reported from Detroit. Jeffrey Collins contributed from Columbia, South Carolina. Russ Bynum contributed from Savannah, Georgia.
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Alexa St. John is a climate solutions reporter for the Associated Press. Follow her on X, formerly Twitter, @alexa_stjohn. Contact her at ast.john@ap.org.
