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April 27, 2011 was one of the biggest tornado outbreaks in United States history, and Alabama was the hardest hit of any state. The day was record breaking for the state. 62 tornadoes touched down in Alabama, the most of any outbreak we’ve got good records of.

Tornadoes by outbreak in Alabama since 1950

In the early morning, a line of storms moved into Alabama from Missisisppi, producing destructive straight line winds and tornadoes. A few tornadoes within this line were quite strong especially in parts of East Mississippi and West-Central Alabama.

KHTX radar data from 2am-8am 4/27/11

In the Tennessee Valley, a second line of storms developed in the mid morning, producing large hail, destructive winds, and tornadoes. As the morning went on, shear increased across the area, and more discrete supercells started to develop in the early afternoon.

KHTX radar data from 8am-2pm 4/27/11

By far, the most destructive round of severe weather came in the afternoon and evening. As deep layer shear and strong instability built into the area ahead of a strong cold front. Supercell thunderstorms developed, and multiple large, violent tornadoes occurred across North and Central Alabama and Southern Tennessee.

KHTX radar data from Noon-4:15pm 4/27/11

By 5:15 pm, communications with the National Weather Service Radar at Hytop were impossible, but tornadoes continued across North Alabama and Southern Tennessee. All told, 39 tornadoes touched down in the Tennessee Valley, and 62 across the state of Alabama. 27 tornadoes across the state would qualify as at least strong (EF2+) and 11 would qualify as violent (EF4+). 3 tornadoes in Alabama received an EF-5 rating.

Major tornadoes across Alabama on April 27, 2011

April 27, 2011 Interactive Tool

A majority of Central and North Alabama was under a tornado warning at some point over the course of the outbreak. For the areas WHNT covers on television, only a small area around parts of Hampton Cove, Owens Cross Roads, Cherrytree, and Berkley in southeastern Madison county and another small area around parts of Liberty Hill, Egypt, Mountainboro, and Walnut Grove in Etowah county were not under a tornado warning. Everyone else, at some point, should have been taking cover.

Tornado warnings across the state of Alabama on April 27, 2011

144 tornado warnings were issued by the National Weather Service offices in Huntsville, Birmingham, and Mobile during the outbreak. 92 of those warnings were issued by the National Weather Service in Huntsville alone.

This tornado outbreak occurred over a 3 day period (April 26-28, 2011) and produced tornadoes from Texas to Michigan and New York, but April 27 was by far the worst of the three day outbreak, and Alabama was hit hardest. 324 people were killed by tornadoes across the U.S. during that three day period. 252 of them were in Alabama. Over 2,000 people were injured in the state of Alabama alone. April 27, 2011 was the single deadliest tornado outbreak day in the U.S. since the Tri-State tornado of March 18, 1925. It remains the single costliest tornado outbreak in U.S. history.

Every single Alabamian has a story about April 27, 2011. It was a day that not only changed the lives of so many people in this state, it also changed the way we communicate risk in meteorology. This day, as well as the Joplin tornado of 2011, led to changes in how life-threatening weather information is communicated to the public. In 2016, a research project called VORTEX-SE was launched, and part of the research involved using social science to determine how people perceive forecasts and warnings, and how to improve them. Some of this research might not have ever happened if not for the terrible loss of life and destruction from this “once in a generation” outbreak. While outbreaks like this are rare, they’re also inevitable. They have happened before, and will happen again. A whole new generation of scientists have been hard at work to try and make sure the next outbreak is even better forecast and claims fewer lives than this one. Hopefully, the advances made because of this horrible outbreak prevent such a horrible loss of life the next time an outbreak like this occurs.

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– Alex Puckett
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