Tropical Storm Lee has been downgraded to a depression, but the remnants are still expected to pose a flood threat to several areas in the Gulf Coast region.

Lee will bring heavy rains to the Central Gulf Coast, the Tennessee Valley and the Appalachian Mountains, the National Hurricane Center has reported.

The NHC warned that heavy rains may also cause life-threatening flash floods and mudslides.

The Central Gulf Coast region is expected to get hit with 10 to 15 inches of rain, according to the NHC. There is also the possibility of isolated amounts of 20 inches of rain through Tuesday.

The NHC predicts that heavy rain will expand northeastward into the Tennessee Valley and Southern Appalachian Mountains through Tuesday. Four to 8 inches of rain are expected. Some areas may get up to 12 inches of rain.

Lee already left 13 inches of rain in New Orleans and 15 inches in the metro areas, as well as spawning tornadoes in Lilliana, Ala., CBS News reported.

New Orleans mayor Mitch Landrieu addressed city residents on Sunday and warned about flooding in the area.

We continue to coordinate with parish presidents and the Governor's Office of Homeland Security, said Mayor Landrieu. We expect the storm to leave the area tomorrow but I encourage everyone to remain vigilant and stay alert.