The week-long tornado outbreak that shattered a world record
Hundreds of tornadoes touched down during a nine-day span in May 2003
A strange pattern that got stuck over the central United States in May 2003 produced four consecutive tornado outbreaks in nine days.
The relentless spell of severe weather ultimately broke the world record for the most twisters ever observed in a single week.
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It’s as if the atmosphere kept hitting copy and paste during the first half of May 2003.
A low-pressure system developed over southern Texas on May 3 and moved into Oklahoma the following day. Warm, unstable air surging northward provided fuel for thunderstorms to flare. Strong wind shear aloft allowed those storms to rotate and produce dozens of tornadoes.
There’s nothing unusual about that kind of setup in Tornado Alley during the peak of severe weather season.
But another low bloomed over Texas on May 6 and triggered a repeat of the destructive severe weather that had caused so much damage just a few days earlier.
Two days later, another storm developed close behind and started the whole process over again. A fourth low-pressure system followed suit on May 10 with the same results.
Four storm systems in nine days caused an unprecedented barrage of twisters throughout the central United States.
Forecasters ultimately confirmed 365 tornadoes in the aftermath of the storms, an event formally known as a tornado outbreak sequence.
More than 330 of those tornadoes touched down in a seven-day period, setting the record for most twisters observed in a single week anywhere in the world.
The ‘swarm’ of tornadoes killed more than 40 people and caused billions of dollars in damages. One of the worst storms struck Moore, Oklahoma, arriving almost four years to the day after an F5 devastated the city.