Northern Florida, coastal Georgia and South Carolina, and parts of North Carolina are bracing for heavy rainfall and catastrophic flooding this week as the Debby storm system moves up and to the east.
Debby came ashore as a Category 1 hurricane on Florida’s Big Bend coast early Monday morning, first striking the small community of Steinhatchee. It damaged homes and businesses, caused rising floodwaters, caused widespread power outages across the state and Georgia, and led to multiple deaths. Debby was downgraded to a tropical storm Monday afternoon.
Experts say the worst is yet to come as the storm is likely to remain over the southeast of the country.
Meteorologists say the system could bring up to 20 inches (51 centimeters) of rain per area in the southeast, with some places even dropping as much as 30 inches (76 centimeters).
That would be a record rainfall, breaking the record set by a tropical system in Hurricane Florence in 2018. More than 23 inches (58 centimeters) of rain were recorded in South Carolina after that storm hit the Carolinas.
Although Debby is classified as a Category 1, “it really deserves a Category 3 or 4 rating, if you want to talk about rainfall impacts,” said Jeff Masters, founder of Weather Underground, now at Yale Climate Connections. “That’s going to cause a lot of damage.”
Northern Florida and low-lying areas, including Savannah, Georgia, Hilton Head Island and Charleston, South Carolina, are expected to experience the worst flooding. North Carolina could also be affected.
Savannah officials warned that the area could get a month’s worth of rain in four days if the system stalls. There were also concerns about flooding for Tybee Island, Georgia’s largest public beach, 18 miles (28.97 kilometers) east of Savannah. On top of the downpours Debby is delivering, the island could get even wetter with 2 to 4 feet of storm surge, the National Hurricane Center said.
“We don’t know how much rain is going to fall. But we have to prepare for the worst,” Hilton Head Island Mayor Alan Perry said in a video posted to Facebook. “If that happens, we’re going to see an event that we’ve never seen before on Hilton Head.”
Meanwhile, Charleston County Interim Emergency Director Ben Webster called Debby a “historic and potentially unprecedented event” three times during a 90-second briefing Monday morning.
Few places in South Carolina are as prone to flooding as Charleston. Much of the city and surrounding areas, founded in 1670, are built on land created by the use of fill and other debris. Rising sea levels cause some minor flooding, even without storms, and like many coastal cities, Charleston does not drain well.
The city is not expecting major flooding from the ocean, but the storm is still dangerous. Heavy rain could flow back into the city, also causing flooding.
According to experts, some hurricanes make landfall quickly, while others move considerably slower.
“What really happened, and why the storm stalled, is because there’s basically high pressure to the west of the storm and to the northeast, and that basically stalled the storm,” said Phil Klotzbach, a senior research scientist in the Department of Atmospheric Science at Colorado State University. “With a hurricane, you’re always going to have wind problems, but when you have a storm that’s moving at 3 to 5 miles per hour, it’s going to be over a specific location for a very long time, so flash flooding and massive rainfall are very likely.”
Experts say warming of the atmosphere plays a role in the severity of storm surges like Debby.
Warming waters in the northeastern Gulf of Mexico are increasing the heavy rainfall from Hurricane Debby as more moisture evaporates from the water, Masters said. Some research suggests that climate change could be affecting the forward motion of hurricanes, he added, causing them to move more slowly.
“It’s something we’ve been seeing more and more lately,” Masters said.
Meteorologists say most of the rain is expected in the first half of the week, but it could last until Saturday.
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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 an Associated Press climate solutions reporter. Follow her on X, formerly Twitter, @alexa_stjohnYou can reach her at ast.john@ap.org.