The day’s highest threat – a level 3 out of 5 – exists for approximately 13.6 million of these people in areas of Alabama, Tennessee, West North Carolina and Georgia, including Atlanta, according to with the forecast center.
Flood monitoring is also in place for areas of central, east-central and southwestern Georgia until Thursday morning, as heavy rains could already flood high rivers and creeks and lead to flash floods, the National Meteorological Agency said.
Conditions in the southeast will begin to worsen as thunderstorms break out just late in the morning, with storms becoming more consistent in the afternoon and continuing into late Thursday night and early Thursday, CNN meteorologist Rob Shackelford said.
The storm system comes as parts of the region are still recovering from recent successive strong weather events, including tornadoes and insidious thunderstorms.
Monday and Tuesday dealt a double blow with severe storms and dozens of reports of tornadoes in Texas, Georgia, South Carolina, Mississippi and Alabama – knocking down trees and power lines as well as damaging homes and businesses.
Thunderstorms killed at least one person in Georgia and another in Texas on Tuesday, local officials said.
A man in East Texas was killed when a tree fell on a caravan in the Whitehouse community, said Smith County Emergency Management Coordinator.
Another died in Georgia’s Brian County as strong weather swept across the area, local officials said. The county, located near Savannah, declared a state of emergency due to the effects of a tornado and imposed a curfew until early Wednesday morning, officials said.
An EF-2 tornado passed through Johnson County, Texas, south of Fort Worth on Monday night, the National Weather Service said. The NWS also confirmed an EF-1 tornado in Collin County and an EF-0 tornado in Johnson County.
A preliminary investigation found that four EF-1 tornadoes hit Mississippi on Tuesday, NWS reported.
The storm trail to the south
As the storm crosses the battered South, different regions will feel the effects at different times. As of 10:30 a.m. Wednesday, the Atlanta subway area and the rest of Georgia are expected to see the strongest chance of tornadoes, catastrophic gusts of wind and heavy hail, Shackelford said. These threats are expected to affect the state until midnight. Later Wednesday, Nashville and parts of Alabama – including Montgomery and Birmingham – also face the same triple threat from 1 a.m. to 11 p.m. As for Carolina, the biggest threats are tornadoes and catastrophic winds, with less chance of hail compared to neighboring countries – although it can not be ruled out. Charleston, South Carolina, can expect to see severe conditions from 6 p.m. until early Thursday. Meanwhile, Charlotte and Raleigh in North Carolina may see strong thunderstorms starting around midnight, with improvements until 7 a.m. Thursday. Correction: An older version of this story overestimated the number of people below the level of the most severe weather threat of the day. About 13.6 million people live in the area with this level of threat. CNN’s Robert Shackelford, Dave Alsup, Gene Norman, Rebekah Riess and Jason Hanna contributed to this report.