A fourth straight day of severe weather is forecast Thursday, this time for the Southeast and Mid-Atlantic, the day after storms killed at least two people in Tennessee and another in North Carolina.

The big picture: Tornado watches were in effect for tens of millions of people from Dallas to Paducah to Nashville on Wednesday evening, as storms erupted from the same major system that plagued parts of the Plains, Midwest and Ohio Valley this week.

TRAFFIC ALERT: 🚨 1 lane is blocked on I-65S at MM 47 in Maury Co. after a reported tornado passed over the interstate. Reports from the scene are that cars and signs in the area were damaged. Our crews are responding to the area. pic.twitter.com/zEEwHSW09u

— Rebekah Hammonds (@RebekahTDOT) May 9, 2024

• In Tennessee, Maury County officials confirmed one person died after a tornado struck near the city of Columbia and the Claiborne County mayor reported on Facebook that another fatality had occurred when a tree fell on a car.
• In North Carolina, an emergency was declared for Gaston County, where one person was killed when a tree fell on a car.

Threat level: On Thursday, a complex of thunderstorms is forecast to congeal over Texas and barrel eastward overnight, bringing the threat of "very large hail," damaging winds and possible tornadoes all the way to Georgia by Friday morning, according to the Storm Prediction Center (SPC).

• Cities in the threat zone include Dallas-Ft. Worth and Arlington, Texas, as well as Atlanta.
• The SPC specifically mentioned the possibility of a long-lasting complex of storms producing widespread wind damage along its path, known as a derecho.

By the numbers: Four tornadoes were reported early Thursday in Tennessee, along with two in Illinois and one each in Kansas, Illinois, Kentucky, South Dakota, Missouri and Texas, according to the National Weather Service.

• More than 80,000 customers were without power in North Carolina early Thursday, per utility tracker poweroutage.us.
• Outages were also reported in Tennessee (over 80,000), Georgia (nearly 32,000) and Missouri (almost 18,000).

State of play: The severe thunderstorms that struck Tennessee and nearby states Wednesday were moving across Georgia Thursday morning.

• A tornado emergency was issued for towns in DeKalb County, in northeastern Alabama, through 11:30pm Central time due to a "damaging tornado," per the National Weather Service. A DeKalb County official reported injuries and "major damage" along a highway in Henagar, per AL.com.
• Another tornado emergency was issued earlier in the evening nine miles east of Columbia, Maury County, Tennessee, due to the "confirmed large and destructive tornado," according to the NWS.
• Trees and power lines were down across the county, Columbia Fire and Rescue said in a Facebook post.
• Flash flood emergencies, the most dire flood warning, were issued for Robertson and Sumner counties, Tennessee, Wednesday evening through Thursday morning after more than 7 inches of rain fell in a short period.

Catch up quick: This spate of severe weather follows the second-most active April for tornadoes, and hits shortly after damaging twisters struck southern Michigan.

The intrigue: Scientists are actively studying how climate change is affecting tornadoes, with some emerging agreement around several points.

• Climate change is affecting the atmospheric conditions that give rise to severe thunderstorms, in particular by increasing atmospheric instability.
• As global air and ocean temperatures increase, the atmosphere can carry more water vapor, a key ingredient for severe storms.
• At the same time, though, wind shear, which is vital for tornado formation, may be decreasing over time.

Between the lines: Some studies show that a warming climate can therefore make tornado outbreaks more prolific when instability and shear overlap, but potentially less frequent because such occasions may be less frequent.

• Tornadoes are small-scale events, making them hard to simulate in most computer models.

Go deeper: The difference between a tornado watch and a tornado warning

Editor's note: This story was updated with additional developments and the latest forecast information.