However, the plains of the United States ​ (a)   the most. (Plains are large areas of flat land with few trees.)

Tornado Alley, a frequent area for tornadoes, ​ (a)   from Texas to North Dakota.

Because tornadoes ​ (a)   over flat areas of land, they ​ (b)   so common in the mountains.

Cold air ​ (a)   warm air, usually in a thunderstorm.

The winds ​ (a)   a spiral or funnel cloud that sometimes reaches 320 miles per hour.

They ​ (a)   cars, trees, and houses.

Sometimes this debris ​ (a)   for miles.

Strong tornadoes ​ (a)   a lot of damage.

Surprisingly, the funnel cloud ​ (a)   long, usually less than ten minutes.

Right now a tornado ​ (a)   over the plains.

People ​ (a)   shelter in underground areas such as basements.

Several storm chasers ​ ​ (a)   ready to follow the tornado and collect data.

They ​ (a)   to weather radios for storm updates.

​ (a)   familiar with tornadoes?

​ (a)   have tornadoes in your area?