At least six people are dead and hundreds of structures in shambles following a disastrous string of tornadoes that ravaged Alabama and Georgia on Thursday.

Some tornadoes were “violent” and “long track,” traveling great distances on their devastating and tireless rampages.

Despite the exceptional impact felt by many and the forecast for widespread severe weather, just three thunderstorms were responsible for spawning these twisters and for most of the casualties and destruction.

These weren’t ordinary thunderstorms, but violently rotating or supercell storms, each exceptional for their duration. The trio lasted hours as they tracked over at least 100 miles, unleashing tornadoes along the way.

At least five people were killed as destructive tornadoes slammed north central Alabama on March 25. (The Washington Post)

The three supercells were responsible for a large portion of the 66 tornado warnings issued Thursday, and all nine of the “tornado emergencies,” the most serious alert used for confirmed, destructive tornadoes in populated areas. They were also to blame for the bulk of the 24 tornado reports logged by the National Weather Service.

Supercells are common in parts of the United States, but Thursday’s were a rare breed, a testament to the extreme availability of energy and spin in the atmosphere. Unfortunately for many residents of Alabama and Georgia, the storms took full advantage of the ingredients in play — and left behind disaster.

Supercell one: Greater Birmingham area

At 11:36 a.m. Central time Thursday, the National Weather Service in Birmingham issued its first tornado warning of the day for an elongated, strung-out thunderstorm cell in west central Alabama along Interstate 20.

Parked over the community of Eutaw, it was zipping northeast at 45 mph. Its rotation, while moderate in strength, didn’t by itself appear overly worrying on radar at first — but the surrounding environment was volatile.

The twister was generated by the first true “supercell” thunderstorm of the day: a lone, individual rotating storm that could tap into the atmosphere’s full fury without competing against neighboring storms for resources. That allowed it to quickly strengthen and coil into an intense circulation. By noontime it was near Akron, a little less than 20 miles south-southwest of Tuscaloosa. It eventually dropped a tornado near Moundville, south of Tuscaloosa along Highway 69, at 12:20 p.m.

By 12:27 p.m., it was confirmed as a “large and extremely dangerous tornado,” and warnings were extended east. At 12:53 p.m., a tornado warning was issued for much of the southern Birmingham metro area.

The storm cycled, meaning its rotation briefly faltered before reorganizing and likely spawning a new tornado. Once again, it was branded as large and extremely dangerous, debris being tossed to more than 13,000 feet.

At 1:37 p.m., the Weather Service opted to declare a “tornado emergency,” the souped-up tornado warning emphasizing a dire situation unfolding in Shelby County. The tornado swept through Helena just north of Buck Creek, crossing Highway 261 near Beef O’Brady’s. It then continued northeast, crossing through several neighborhoods and storming across Highway 119 in Pelham near Crosscreek Trail.

Interstate 65 was impacted next — then Indian Springs Village, Lunker Lake and the Eagle Point neighborhood off Highway 280 in particular. That’s where dozens of homes were demolished, some brick structures collapsing in on themselves. At least five people were killed.

A tornado was confirmed northeast of Pell City, Ala., about 30 miles east of Birmingham, at 2:27 p.m. Damage continued farther north and east all the way to north of Piedmont in Cherokee County, which borders Georgia, until nearly 3:25 p.m.

That’s a staggering 140-mile-long damage track — likely resulting from a tornado family that accompanied the supercell over nearly four hours. At least five people perished in the disastrous storm, which rivaled some of the infamous long-track supercell thunderstorms that ravaged the area on April 27, 2011. Damage to some structures may have been in the EF3 to EF4 range.

Supercell 2: Greensboro-Brent-Columbiana-Calera, Ala.

While the previous storm was ongoing, little else was happening across the state in terms of tornado activity, leaving many to wonder if the event was underperforming with regard to areal coverage.

Around 3:30 p.m., however, a maturing thunderstorm crossed the border from Mississippi into west central Alabama, showing signs of rotation south of Interstate 20. The Weather Service issued a lengthy downwind tornado warning at 3:59 p.m., betting on an intense tornado that could persist for an extended period of time.

A massive doughnut hole eventually appeared on radar, marking where the developing tornado’s updraft was so strong that heavy rain was suspended and unable to fall, leaving a narrow void. That’s called a BWER, or Bounded Weak Echo Region. Intense rotation was evident on radar; no storms were present to the south, either, allowing warm, moist air to flow into the storm unimpeded.

A large wedge tornado was spotted west of Greensboro, and at 4:40 p.m., a tornado emergency was hoisted for northeastern Hale County, Ala.

“A large, extremely dangerous, and potentially deadly tornado is on the ground,” warned the Weather Service in Birmingham, who deemed the threat level as “catastrophic.”

The tornado plowed east, passing just south of Brent and Centreville, and even impacting areas south of Birmingham, like Calera and Columbiana. Radar suggests the tornado may have had violent winds of 150 mph or greater, with debris carried 20,000 feet high into the atmosphere.

Unlike with the first supercell, which produced a tornado family, it appears that the damage left by this supercell may have been from a single extremely long-track tornado, with a path length of around 100 miles. The tornado spared downtown Brent and Centreville, but wrecked several homes to the south and plowed down a swath of forest more than half a mile wide.

Supercell three: Newnan and Peachtree City, Ga.

Just when most had believed the outbreak was over, a third supercell thunderstorm charged into eastern Alabama. At 9:51 p.m., the Weather Service, again in Birmingham, issued a tornado warning for areas northeast of Alexander City near the Talladega National Forest. Seven minutes later, it was a confirmed tornado, and before long it was listed as “large and extremely dangerous.”

The tornado moved east at 60 mph, impacting Crystal Lake, Ala., and tossing debris to 10,000 feet. Then it crossed the border into Heard County, Ga., and intensified. Newnan, Ga., home to nearly 40,000 people, sustained a direct hit from the tornado, which passed over thickly settled neighborhoods and at least the southern part of the historic downtown district. The city was struck around midnight Thursday.

“Please… get off the road in Newnan,” the Newnan Police Department posted on Facebook after the storm roared through. “We have a large … amount of damage. ... By you being out and sightseeing… it is impeding our efforts to get to people that need help.”

A debris ball appeared on radar where the cluttering of shrapnel, vegetation and pieces of homes and businesses picked up by the tornado was so dense that it reflected high quantities of radar pulses back to the radar dome.

The tornado eventually swept near or north of Peachtree City, crossing Highway 74. Doppler radar revealed debris being carried so high that jet stream winds fanned light materials into the southern suburbs of Atlanta.

While reports thus far indicate this supercell waited until eastern Alabama and northern Georgia to produce a tornado, it had actually formed hours earlier, around 4 p.m. Eastern, in southeast Louisiana and traveled several hundred miles before it became a twister-producer.