2011 Super Outbreak (tornado)

The 2011 super outbreak began on April 25 and lasted until April 28 with the majority of tornadoes occurring from the 26 of that month to the 28th with the 27th being the most active and destructive day with 199 tornadoes recorded in that 24 hour period. These tornadoes occurred across the southern, central and eastern United States and affected the states of Mississippi, Alabama which fared the worst amongst all the states affected, Florida, Georgia, South and North Carolina, Tennessee, Arkansas, Missouri, Virginia, West Virginia, Maryland, Indiana, Ohio and New York. The outbreak began on April 25th when a strong cold front approached the Gulf of Mexico, where the dew points and moisture levels were high and the perfect amount of wind shear was present to give the perfect setup for supercell thunderstorms and tornadic activity. On April 25 the main storm activity was over Northeast Texas, Kentucky and Tennessee with the majority of the 69 recorded tornadoes being less than EF2 in intensity. The following day saw the similar set up over the same area with 50 tornadoes recorded over Eastern Texas to Western Kentucky. But the following day on April 27th was a recorded breaking day with over 199 tornadoes being recorded over that 24 hour period with some estimates being at 207 tornadoes. This day spawned deadly and destructive tornadoes across the entire south with the worst being in the state of Alabama where a EF4 tornado flatten towns and destroyed 10% of the residential area in Tuscaloosa, this particular storm tracked over 80 miles and was part of a thunderstorm cluster that had produced tornadoes over a 342 mile stretch from Mississippi to North Carolina. The Tuscaloosa was not the only strong tornado recorded that day but there was also 3 EF5, 12 EF4 and 21 EF3 tornadoes that struck throughout Mississippi, Tennessee, Georgia, Alabama, and Kentucky that afternoon into the evening. The day following the active day on the 27th we saw another 43 tornadoes reported from the residual system that spawned from Georgia to New York with 4 EF2 and one deadly EF3 twister that spun up with the rest being less EF1 or EF0. Over the course of the outbreak there were 300 tornadoes recorded across 15 states beating the previous record that was made during the 1974 Super Outbreak that spawned 148 tornadoes and killed 315 people.

EF4 Tornado damage over Tuscaloosa, Alabama following the tornado outbreak on April 27, 2011

Map of confirmed tornado touchdowns from April 26 to April 28, 2011

The month of April in 2011 was considered the most deadliest and destructive outbreak since records began in 1950 with about 90% of the supercells of the course of the April Super Outbreak producing at least one tornado with many being long tracked and intense. The outbreak had cost the United States 11-15 billion dollars in damage with just the debris cleanup in Tuscaloosa being around 100 million alone. The importance of this event is that even with the level of early warning that was provided by the National Weather Service Forecasting Offices there was still a high level of deaths at 315 people and 2900 injured showing the need for better awareness over these dangerous storms and education over what to do when there is a tornado watch or warning as this information is crucial in moments leading up to a severe weather event. This event destruction could not have been prevented as many of these storms went through suburban and urban centers causing 10 million cubic yards of debris as even with early warning systems and forecasting in place there was still widespread devastation and deaths. But one method to help prevent further events like this is to mitigate climate change as currently with the warming that has occurred there has been an uptick in the number of tornadoes with many researchers believe that climate change will increase the amount of tornadoes especially after the 2 degree warming point. But currently there is still disagreement on if global warming will contribute to more storms or not as the warm air from the gulf could cause the cold air from the Rockies to warm up causing less wind shear for the storms to form on, but at the same time extra moisture coming from the warming gulf could help intensify the contrast between the two air masses making storms more plausible. But one thing that all researchers are coming to agreement on is that climate change is causing tornadoes to shift their range as the dry 100 meridian moves eastward, and with this movement we are seeing tornadoes become more common eastward and northward into the southeast and great lakes regions.

Graphic showing in recent times tornadoes are increasingly occurring more east of the original tornado alley

This video explains the ingredients in place for this super outbreak to happen and how this is the second named super outbreak. The video also talked about records that were broken during the month of April in regards to Tornadoes and the timeline of these storms. 

References:

Amadeo. K. (2020). Tornado Damage to the Economy. Thebalance. https://www.thebalance.com/tornado-damage-to-the-economy-3305667

Knupp, K. R. and Coauthors. (2014). Meteorological overview of the devasting 27 April 2011 Tornado Outbreak. Bull. Amer. Metero. Soc. 90, 1041-1067. https://doi.org/10.1175/BAMS-D-11-00229.1.

Rafferty. J. (2020). Super Outbreak of 2011. Encyclopaedia Britannica. https://www.britannica.com/event/super-outbreak-of-2011

Sosnowski, A. (2019). Remembering the deadly super tornado outbreak of 2011. Accuweather. https://www.accuweather.com/en/weather-news/remembering-the-deadly-super-tornado-outbreal-of-2011/331951

WeatherNation. (2019). April 27, 2011 super outbreak: 8 years later. WeatherNation. https://www.weathernationtv.com/news/2011-super-tornado-outbreak-look-back/