Charleston, Southeast face flash flood threat as stubborn front drops torrential rains

A slow-moving cold front that helped protect the Eastern Seaboard from a direct strike by Hurricane Erin is now set to soak much of the South and Southeast Friday, dampening the end of the week and bringing a risk of flash flooding.

The front has been slowly cutting south across the East but is running into an atmospheric roadblock on Friday as it reaches the Gulf Coast, according to the FOX Forecast Center. And while Hurricane Erin is now racing away from North America, strong flow behind the storm is smashing into the frontal boundary, enhancing the available rainfall for Friday.

The greatest risk of flash flooding will stretch from around Charleston, South Carolina, through that state’s Low Country and into southeastern Georgia, including Savannah. 

NOAA’s Weather Prediction Center (WPC) has issued a Level 2 out of 4 flash flood risk for the area, while the National Weather Service has Flood Watches in effect.

With storms lingering into Saturday, rainfall rates there could reach 2-3 inches per hour in heavier and slow-moving thunderstorms, with some storm totals reaching 3-5 inches by later Saturday.

But while the flash flood risk is lower across the rest of the Southeast and Gulf Coast, rainfall totals will still likely reach 1-2 inches through the weekend as the front hangs around.

The WPC is maintaining a Level 1 risk across much of the area for Saturday, but it may be upgraded if moisture trends continue to increase, according to the FOX Forecast Center

Cold front led to Flash Flood Emergency in Virginia

The front has already left its flooding fingerprints in the mid-Atlantic.

On Thursday night, flash flooding hit parts of Southwest Virginia and Northern North Carolina, where some areas saw nearly 5 inches of rain in just three hours.

Roanoke, Virginia, received a whopping 3.39 inches of rain in just one hour, triggering a Flash Flood Emergency.

The NWS reported nearly a dozen high-water rescues as streets became submerged and vehicles stalled.  

The city’s daily rain total of 4.27 inches, which fell in just two hours, was the third-wettest August day in the city’s history and the fourth-wettest date since 1980, the NWS said.

Forecasters there said that corresponded to about a 1-in-500-year flood event, or about a 0.2% chance of rainfall of that magnitude occurring in any given year.