Document-Based Questions - Debra J. Housel, M.S. Ed. 2008

The World’s Worst Tornado
Incredible Disasters

The world’s worst tornado happened in the United States. The Great Tri-State Tornado spun through three states on March 18, 1925. It left a trail of wreckage 219 miles long. Over 11,000 homes were lost. Even worse, the storm killed 695 people. It left about 2,000 hurt.

The Great Tri-State Tornado made two records that stand to this day. It had the longest contact with the ground, and it lasted 3.5 hours. It raced through Missouri, Illinois, and Indiana. Of those, just Missouri is a “Tornado Alley” state. Tornado Alley lies in /the center of the United States. About 90 percent of all twisters form there. Why? Cold, dry air, and warm, moist air meet over the Midwest. About 1,000 twisters occur each year, often in spring or summer. It’s a good thing that most are weak. There is no way to stop tornadoes. If one forms, people must get out of its way!

How do tornadoes start? Supercells give birth to twisters. When strong winds blow in opposite directions, a supercell thunderhead* forms. The air inside the thunderhead spins. If an updraft knocks this spinning air on end, it may form a whirling funnel. The funnel drops to the base of the thunderhead. If it touches the ground, it’s a tornado. Then it smashes anything in its path. It can pick up houses and dump them a mile away. It can toss a train engine around like a cotton ball.

The Great Tri-State Tornado was deadly because people had little warning. Most people were inside their homes. Low storm clouds made the sky too dark to see the funnel. And the storm moved fast— about 70 miles per hour.

Now fewer people die from tornadoes. Doppler radar can detect a hook-shaped swirl within a cloud. That may mean that a twister is forming. People are warned right away. Then they can take shelter. In May 1999, an Oklahoma twister had wind speeds of 318 miles per hour. That’s the highest wind speed ever recorded on Earth. At more than one mile in width, it was also the largest tornado ever recorded. But since people had warning, just 46 died. That’s a fraction of the Tri-State Tornado’s death toll.

*towering clouds that have winds blowing up and down within them

The World’s Worst Tornado

The World’s Worst Tornado

1. About how many tornadoes form in Tornado Alley each year?

a. 219

b. 295

c. 1,000

d. 11,000

2. When people have warning of a tornado,

a. the death toll goes down.

b. the death toll goes up.

c. they have time to get in their cars and drive away.

d. they can storm-proof their homes.

3. Which state is not in Tornado Alley?

a. Missouri

b. Oklahoma

c. Nebraska

d. Illinois

4. Every supercell thunderhead will cause a tornado. True or False? Explain.

5. Tornado Alley states have a clash between cold and warm air. Look at the map. Where does the cold air come from? Where does the warm air come from?

6. When people are warned that there’s a tornado in the area, should they take the time to get family photos or other valuables before seeking shelter? Why or why not?