Debby may bring more rainfall than 2015's 1,000-year flood, S.C. officials say

State government and weather officials are warning of potentially “catastrophic” rainfall and flooding along the coast and Pee Dee/Midlands with 4-10 more inches of rain from Tropical Storm Debby predicted than the 1,000-year flood in 2015.

That does not mean the same areas will flood as they did after Hurricane Joaquin nearly 10 years ago or that they’ll flood as badly. In fact, a National Weather Service representative said Monday, “likely some areas that have never flooded in the past will flood this time.”

Sumter, Clarendon and Lee counties are under a flood watch through the evening of Thursday, Aug. 8, as Debby slowly moves through the area this week.

Heavy rainfall is expected across the area with 5-10 inches, and locally higher amounts, along and south of Interstate 20, according to the National Weather Service on Monday.

“Eight to 12 inches is not out of the question” in localized areas of Sumter County, said Emily Carpenter, NWS Columbia Office meteorologist. During a media briefing Monday afternoon, NWS Warning Coordination Meteorologist John Quagliariello said the forecast is for a “confident prolonged period of impact” through late this week, with “catastrophic flash and urban flooding” resulting from up to 30 inches of rainfall along the coast from Beaufort to Charleston.

“They’re underwater almost to begin with,” Gov. Henry McMaster said about Charleston.

Officials said Monday the aftermath of Joaquin, which brought Sumter residents to canoe through their neighborhood and out of damaged homes, during the 2015 flood saw up to 26 inches of rain, though many areas were more around 20 inches.

With showers starting tonight and heavy rain coming Tuesday morning from the storm, which made landfall as a Category 1 hurricane in Florida where the peninsula meets the Panhandle in the north before quickly downgrading to a tropical storm, Debby is poised to dump rain on already-saturated ground.

NWS’ Sumter station recorded 1.49 inches of rain Aug. 3-4, though Carpenter said there are places in Sumter “that probably got more based on our radar rainfall estimates.” The Manning station received 1.13 inches in those 48 hours, and Bishopville tallied 2.52 inches.

“That’s not good looking forward to the precipitation for Sumter this week,” Carpenter said, noting the Sumter area is predicted to notch some of the heaviest inland rainfall totals from Debby.

Monthly normal average rainfall totals for July are 5.75 inches for Sumter, 6.22 in Manning and 4.53 for Bishopville. This July, Sumter received 3.32 inches after starting off very dry then accumulating rainfall toward the end of the month. Manning received 4.25 inches and Bishopville 6.06.

Ahead of the storm, state officials said lakes Marion, Moultrie and Murray have been lowered.

McMaster issued a state of emergency to implement emergency operations, though no state facilities or agencies are closing as of Monday. No evacuation orders are in place either, similar to 2015. Local municipalities may issue their own orders.

No local shelters are open as of now, though officials are monitoring the situation. As of Monday, three shelters are open along the coast, with four more poised to open as needed.

According to the Associated Press, President Joe Biden has approved a request from McMaster for an emergency declaration, following his earlier approval of a similar request from Florida.

In a statement to AP, the White House said personnel from the Department of Defense, the Department of Homeland Security, the U.S. Army Corps of Engineers and the U.S. Coast Guard are deploying to the region and are prepared to support recovery efforts.

Debby has been blamed for four deaths in Florida as it swept to Georgia on Monday, with a curfew announced in Savannah, Georgia, ahead of “unprecedented rainfall” and the mayor of Hilton Head warned tourists and residents to not let their guard down, AP reported.

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