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04/24/2013

The 2011 Dixie Alley Super Outbreak!

It was on this date two years ago that the largest sequence of tornadoes in recorded history began over the Southeastern United Sates.  

56189_tuscaloosa-tornado_u4otpkuoohegc34cxym6cgqbe3ncurxrbvj6lwuht2ya6mzmafma_610x457Tuscaloosa, Alabama - April 27, 2011

During the four day period between April 25th and April 28th 2011 an astonoshing 358 tornadoes occurred from Texas through Georgia and as far north as New York and Southern Canada!  

205 tornadoes touched down on April 27th alone, making it the most prolific tornado outbreak every recorded even surpasing the raw number of tornadoes produced during the Super Outbreak of April 3, 1974.

In total, 348 people perished during the four day series of outbreaks with 238 fatalities occuring in the hardest hit state of Alabama.  

The concrete stairs are all that remain of this Tuscaloosa, Alabama home following the devastatingConcrete stairs are all that remain of this Tuscaloosa, AL home destroyed by a strong EF-4 on April 27, 2011

The storm was well advertised.  The Storm Prediction Center warned of the possibility of a mega outbreak several days in advance and highlighted much of the Southern and Eastern US on day 4 and 5 outlooks.

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In an unprecendented fashion, SPC issued Moderate and High Risks for severe weather on three consecutive days covering April 25th, 26th and the 27th.  

SPC Severe Compilation2Click image for a full view of SPC Outlooks

The long duration event was driven by a very strong and slow moving upper level trough of low pressure that had dug deep into the Southern Plains during the April 24th through the 26th time frame.  

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By the 27th, the powerful upper storm system began to eject eastward into the Southeastern US with jet stream winds in excess of 140 mph. 

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These high speed, upper level winds combined with a super warm and moist air mass at the surface to produce an absolute explosion of thunderstorms on the 27th.

                 Visible Satellite Loop - April 27, 2011

Similar to what occurred on April 3, 1974, every storm that developed that day began to rapidly rotate producing a swarm of tornadoes.  

           National Weather Service NEXRAD Doppler Radar Loop out of Birmingham on April 27, 2011

This prompted the National Weather Service to issue an unbelievable number of Tornado Warnings across Mississippi, Alabama, Georgia and into Tennessee during the peak of the event on April 27th. 

 April_27,_2011_severe_weather_warningsMap of all tornado (red), severe thunderstorm (yellow), and flood (green) warnings issued on April 27th.

Not only were there an extreme number of tornadoes, many of them grew to monsterous proportions with 44 tornadoes being assessed as strong, EF-3 or greater in intensity and four of them were classified as EF-5!

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To put this in perspective, the US only averages around one EF-5 per year.

This rivals only the 1974 Super Outbreak that produced 63 strong tornadoes and a staggering six EF-5's. 

Tornado-limestone-county-alabamajpg-e3e01a276fb6b647EF-4 Tornado in Limestone County Alabama on April 27, 2011

Dick McGowanEF-5 Tornado Near Philidelphia, MS.  Photo Courtesy Dick NcGowan and TornadoVideos.Net

Image of a strong tornado near Arab Ala Credit Charles WhisenantEF-4 Tornado near Arab, Alabman on April 27, 2011.  Photo Courtesy Charles Whisenant

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Tornado Damage Path north of Birmingham Alabama


          YouTube Video of Hackleburg and Phil Campbell, Alabama tornado Courtesy Josh Taylor


 YouTube Video of EF-5 Tornado near Philidephia, MS - Courtesy Reed Timmer and TornadoVideos.Net


Although April 27th 2011 was by far the largest outbreak of tornadoes that has occurred in recent history, it was a part of a much larger sequence of tornadoes that occurred in late April of that year.

SPC Severe CompilationClick on this image to see the staggering amount of severe reports that occurred from April 24th through April 28th of 2011

Wikipedia - April 25 - 28, 2011 Tornado Outbreak

The 2011 severe weather season went on to produce the catastrophic Joplin Missouri EF-5 and will go down as the deadliest year for tornadoes in the last 60 years. 

In total, 540 people perished due to tornadic storms in 2011.  This compares to only 564 that were killed by tornadoes during the 10 year period from 2001 through 2010. 

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Hopefully, we don't see a season like this one again anytime soon!


Meteorologist Jeremy Kappell

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