10 Years Later: What We Learned From The 2011 Tornado Super Outbreak

Image Source: Dusty Compton/Tuscaloosa News, via Associated Press

The April 25-28, 2011 Super Outbreak remains one of the worst tornado outbreaks in U.S. history, claiming more than 300 lives and injuring 1,775. 

The above animation shows lowest-level doppler radar reflectivity (dBZ), and surveyed/confirmed tornado tracks mapped to the Enhanced Fujita (EF) scale (EF0 – EF5) from April 24–28, 2011. Animation by John L’Heureux, Atmospheric Data Scientist at Tomorrow.io


The above animation shows lowest-level doppler radar reflectivity (dBZ), and surveyed/confirmed tornado tracks mapped to the Enhanced Fujita (EF) scale (EF0 – EF5) from April 24–28, 2011. Animation by John L’Heureux, Atmospheric Data Scientist at Tomorrow.io

More than 350 tornadoes touched down across 21 states. On April 27th alone, officials tallied 199 tornadoes across 15 states, a record for any calendar day in the U.S. 

In addition to the fatalities, the Super Outbreak resulted in $12 billion in total damage. 

Now on the 10th anniversary of the 2011 Super Outbreak, we’re looking back on the days leading up to the outbreak, where some of the most violent tornadoes occurred, and research determined to learn the cause of these violent tornadoes. 

Chief Scientist at Tomorrow.io, Daniel Rothenberg, said, “It was very strongly telegraphed in advance that this was going to be a big one.” 


Looking back at the map of tornadoes from this Super Outbreak, Daniel said, “You never see a map with this much red and blue. You never see something that’s a third of the entire country. This simply doesn’t happen.”

Though there were warnings in advance, people were still shocked by the tornado outbreak. 

“I think the shock and awe of it was the magnitude and spread, both in space and time of this event. It’s very, very rare to get these types of outbreaks that impact so many people for such a long duration of time,” Daniel said. 

The outbreak spanned four days, starting on April 25, but many remember the 27th as the most violent and devastating day. 

“In the morning on the 27th, there was a significant line of thunderstorms that went through southern Tennessee and did a lot of damage — brought tornadoes, flash flooding — and then the event just continued,” Daniel said. 

Daniel said the EF5 tornado in Smithville, Miss. was so intense it dug a trench in the ground.

“The most dramatic one was the Tuscaloosa, Alabama tornado. Very strong and violent EF4, which also didn’t fit the normal visual description of a tornado, like this slender thing. It was a wedge almost a quarter of a mile wide,” Daniel said. 

Nearly 350 tornadoes over four days is a rare event, so why did this happen? 

What Caused The Outbreak?

Daniel said the simple answer is that you can get these massive events in the U.S. when specific weather patterns line up. They happen every couple of decades or so. The most similar tornado outbreak to 2011 is the Super Outbreak of 1974. 

However, the 2011 Super Outbreak inspired various interesting studies looking for more in-depth answers. Notably, one study looked at how smoke may have contributed to the outbreak. 

“One of the really interesting research published in the aftermath of this looked at the implications of smoke and wildfires that had been burning in Central America,” Daniel said.  

Research showed some indication that smoke transported from Central American into the southern part of the U.S., detailed in an article by National Geographic.  

He said this research brought up the question of whether this smoke modified the environment or amplified what happened. 

“There’s a really interesting bit of climate physics on how particles and aerosols that we admit into the atmosphere, and that would include wildfire smoke, can sometimes invigorate or enhance convection or thunderstorms,” Daniel said. 

This study concluded that the Central American biomass burning smoke could increase tornado severity in the U.S.; however, Daniel noted that nothing has been proved definitively. There’s still ongoing research looking into all the factors that contributed to the magnitude of this outbreak.

Researchers from the study said they hope the findings encourage meteorologists to consider air pollution as a risk factor when making tornado forecasts.

Additionally, the 2011 Super Outbreak led to many social science research on how we can better communicate severe weather and tornado risks to communities. 

The Southeast: Another Tornado Alley 

While most people connect midwestern states with tornadoes since Tornado Alley spans the Central United States, the southeast, known as “Dixie Alley,” is just as prone to tornado outbreaks. 

“By many accounts, the southern part of the United States—Mississippi, Georgia, Alabama, South Carolina, and North Carolina to some extent—are just as active a tornado zone as our traditional Great Plains and Tornado Alley,” Daniel said. 

Topography and population density make Dixie Alley even harder to track. 

“This [Dixie Alley] is a very challenging part of the country for forecasting, observing, and monitoring tornadoes. The topography, consisting of hills and trees, makes it difficult to get a good visual confirmation when there is a tornado on the ground,” Daniel said. 

While a tornado in Kansas may touch down in an empty field, a tornado in Alabama has a much greater chance of hitting people, businesses, and homes. This puts a greater emphasis on the importance of weather technology and equipping individuals with an accurate forecast. 

“The work we do matters. The weather isn’t just some picture on the screen. There are certain totalities of it that very much and very greatly impact people on the ground,” Daniel said. 

Staying ahead of and tracking the weather is the first step people can take to stay safe. Whether it’s watching the nightly news or using an app like Weather by Tomorrow.io—knowledge is preparedness.