Tornado Damage to the Economy

Worst Tornado Damage Ever

••• Rare double tornado touches ground. Photo: Rui Almeida Fotografia/Getty Images

The first quarter of 2017 was the worst for insurers in 20 years. Tornadoes were a large part of that. There were 425 tornadoes between January and March. That's more than double the 205 tornadoes during the same period in 2016. On average, there were 93 tornadoes in each the first quarters of 2014 through 2016. It's unusual for tornadoes to occur that early in the year. May is typically the worst month.

Worst Tornado

The most damaging tornado ever was May 22, 2011, in Joplin, Missouri. It cost $2.8 billion. That's $2.9 billion when adjusted for inflation. It was also the most deadly tornado since 1950. Sadly, 161 people were killed, and more than 1,000 were injured. More than 500 businesses were severely damaged, affecting 5,000 workers. 

The EF-5 tornado was 1/2 mile wide when it touched down at the western part of the city. It expanded to 3/4 mile in width. It traveled 13 miles in all, hitting the City of Duquesne as well. Winds were 200 miles per hour, and it traveled about ten miles per hour. (Source: "Joplin, Missouri Hit by EF-5 Tornado on May 22, 2011," City of Joplin. "Joplin Tornado," National Weather Service)

Worst Tornado Season

The most damaging tornado season occurred April 25-27, 2011. In that week, 305 twisters hit the Southeast, breaking the 1974 record of 267 tornadoes. The outbreak caused $5 billion in damage.

At least two of the storms were EF-5 twisters, producing wind gusts of more than 200 miles per hour.

The tornado outbreak killed 327 people, with 250 dead in Alabama alone. It was the third-deadliest single outbreak in U.S. history. The worst was March 1925, when 747 people died. The second-worst was March 1932, when 332 perished.

That outbreak made April the most active month for tornadoes ever, with 600 tornadoes forming. The previous record was 542 tornadoes in May 2003. It also brought the year's total to 881 tornadoes, almost half the tornado record of 1,817 set in 2004.  (Source: Bloomberg, "Deadly Tornado Outbreak May Be Worst in History," May 4, 2011)

What Causes Tornado Damage?

Tornadoes usually hit east of the Rockies during the spring and summer. On average, 800 tornadoes hit a year, killing 80 people and injuring 1,500 more. Since 2008, that average has increased to more than 1,300 a year. The most violent tornadoes can have wind speeds of more than 250 mph and leave a damage path a mile wide and 50 miles long.

A tornado is any violently rotating column of air extending from a thunderstorm to the ground. Tornado-producing thunderstorms develop in warm, moist air in advance of eastward-moving cold fronts with dry air, known as a "dryline." The United States is the world's "hot spot" for tornadoes, thanks to a combination of large land mass (the Great Plains) that warms on hot days, a cold, dry wind from the Rockies, and warm moist air from the Gulf of Mexico. The earth's jet stream swoosh all these together to create Tornado Alley.

The damage from a tornado depends on whether it hits rural or urban areas. The costliest tornado outbreak occurred May 4-11 2003. At least 100 tornadoes hit eight states, including Kansas City, Oklahoma City and Jackson, Tennessee. The damage was $3.2 billion. The Sage of Omaha, Warren Buffett, warned that natural disasters  pose a greater threat to the economy than terrorism.

Does Global Warming Increase the Number of Tornados?

Some say global warming is increasing tornado damage. That's because the Gulf of Mexico is becoming warmer. It increases the contrast when it hits the cold air from the Rockies. But others argue that global warming is reducing the number of tornados. That's because the warm Gulf air warms the cold air from the Rockies.

Two separate studies in 2007 reported that climate change could increase the type of weather conditions that feed tornadoes.

In the Proceedings of the National Academy of Sciences, Jeff Trapp of Purdue University said the number of days that generate severe thunderstorms could double by the end of the century. NASA research scientist Tony Del Genio agrees that tornado activity may be on the rise. Del Genio developed a computer model to research the impact of global warming on tornado activity. According to his research, global warming increases the likelihood of strong updrafts. That's when the wind moves up and down instead of sideways, which is like an incubator for tornadoes. The computer model predicted that global warming would create the conditions most likely to result in the most damaging tornadoes. 

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