Why the size of the Mississippi tornado was remarkable

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The tornado that pummeled through west-central Mississippi on Friday was large, destructive – and exceptionally rare. It caused at least 25 deaths in the state along a path of 59.4 miles, according to post-disaster surveys by the National Weather Service (NWS).

Approximately 67,000 tornadoes have touched down in the United States since 1950, with an average path of under four miles. Less than 1 percent of tornadoes in the United States travel more than 50 miles, according to a Post analysis of NWS data recorded between 1950 and 2021. Just 1 in 1,100 tornadoes cover more than 100 miles.

The tornado touched down near Rolling Fork – located about 60 miles from Jackson, Miss. – and continued on to Silver City, staying on the ground for more than an hour. With maximum winds of 170 mph, it received a preliminary rating of 4 out of 5 on the NWS’s Enhanced Fujita Scale that assesses tornadoes based on their estimated wind speeds and related damage. It is one of the deadliest tornadoes recorded in the state.

After it lifted off the ground, another tornado formed from Blackhawk to Winona and covered a path of 28.6 miles, according to post-disaster surveys. This tornado, which had maximum winds of 155 mph, received a preliminary rating of 3 on the Enhanced Fujita Scale.

The rotating thunderstorm, or supercell, that spawned these and other tornadoes brought 170 miles of destruction across Mississippi and Alabama, said Lance Perrilloux, a meteorologist at the National Weather Service office in Jackson.

“We just didn’t think it was going to last that long,” Perrilloux said. “The ingredients were there. They were forecast to be there, but just to actually see it, it’s just something you can’t prepare for.”

The longest tornado recorded in U.S. history was the 219-mile-long Tri-State tornado on March 18, 1925, which tore through southeast Missouri, southern Illinois and southwest Indiana and killed nearly 700 people.

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How common are long-track tornadoes?

Long-track tornadoes are rare, Perrilloux said, because tornadoes need a very specific set of requirements to stay alive. A variety of physical processes taking place inside a rotating thunderstorm can shorten a tornado’s life span. Subtle changes in air temperature, wind or humidity from location to location can also cause a tornado to weaken or dissipate. For example, winds that shift from coming out of the south to coming out of the north can shut down a violent storm.

“The fact that all of the ingredients were in place for that tornado to survive that long is what makes that very rare,” Perrilloux said, “because literally the atmosphere can change within seconds.”

The path length of a tornado also depends on the storm’s motion, said John T. Allen, a meteorology professor at Central Michigan University who researches severe storms. Friday’s storms were moving at about 55 to 60 mph – the average speed of a tornado is 30 mph – propelling long-lasting tornadoes to cover more ground.

These types of events – fast-moving and long-tracked tornadoes occurring at nighttime – disproportionately affect the Southeast, said Allen. In recent memory, the deadly Mayfield tornado stayed on the ground for 165.7 miles as it tore across parts of Kentucky one night in December 2021.

Warmer temperatures in the Southeast create more instability necessary for tornadoes. The Southeast also has a high population density in mobile or manufactured homes, which often have poor anchoring to the ground, making them especially vulnerable to violent tornadoes.

“While it is not an every-year occurrence, we unfortunately see this type of event all too regularly in the Southeast, though not always with a tornado of this intensity,” Allen said. “Many of the residents in these regions do not have access to the sorts of shelter needed to withstand this type of event, and the recovery will be a difficult process.”