Moisture from Tropical Storm Bertha intensifies flood risk across Mid-Atlantic and Southeast

Tropical Storm Bertha, centered south of the Louisiana coast with sustained winds of about 45 mph, is forecast to move along the Louisiana and upper Texas coasts on Thursday before turning inland and dissipating over Texas by Friday. The storm could bring 2 to 4 inches of rain, with isolated amounts up to 6 inches, to the Texas Gulf Coast, raising the possibility of flash flooding.

At the same time, a plume of tropical moisture from Bertha is merging with a cold front over southeast Virginia, the Carolinas and northern Georgia, amplifying rainfall in the Mid-Atlantic and Southeast. The combined system has already produced bands of rain in eastern Tennessee, southern Virginia and northern North Carolina, prompting flash-flood warnings north of Knoxville after up to 5 inches fell in a few hours.

Meteorologists warn that additional rain is likely through Friday, with some locations potentially receiving a month's worth of precipitation in just a few days. A Level 3 of 4 flood-risk rating has been issued for parts of the Virginia-North Carolina border for Thursday into Friday morning, and thunderstorms could deliver rates of up to 2 inches per hour, overwhelming drainage systems. Cities such as Atlanta, Birmingham and Charlotte are among those facing heightened flood concerns. A Level 2 of 4 risk extends from coastal North Carolina through South Carolina, northern Georgia and northeast Alabama on Friday, with the possibility of an upgrade as forecast models refine the expected rain distribution.