Did you know that the United States has the highest incidence of tornadoes in the world? Before you are caught in a storm, be prepared with these tornado safety tips.
Where Are Tornadoes Most Common?
In the U.S., an average of 1,200 tornadoes form each year, many of which occur in an area called “Tornado Alley” (a region covering all or parts of Arkansas, Iowa, Kansas, Louisiana, Minnesota, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota and Texas).
Why there, you ask? Located in the Great Plains, this area receives cold polar air from Canada, warm tropical air from Mexico, and dry air from the Southwest, which all clash in the middle of the country. Heat and moisture can build up near Earth’s surface if a stable air layer called a “cap” lies on top. Then, if the cap weakens, the lower, unstable air rises rapidly, often forming super-cell thunderstorms that are the harbingers of tornadoes.
Statistics show that most tornadoes in the U.S. occur between 5 P.M. and 6 P.M. However, those times vary by region; for example, Florida tornadoes are just as likely to occur after midnight as in the afternoon.
Although the U.S. is certainly a hotbed of tornado activity, tornadoes do happen in other parts of the world. Significant tornadoes have been recorded in Canada, Mexico, Argentina, Brazil, Australia, Russia, Bangladesh, South Africa, and the United Kingdom, among other places. In fact, the deadliest tornado on record occurred in April 1989 in Bangladesh, where a tornado reportedly killed more than 1,200 people after two entire towns were leveled.
Where Are Tornadoes Uncommon?
Luckily, tornadoes don’t touch down very often in the downtown centers of big cities. Tornadoes require three factors to grow: vertical air movement, which generally comes from thunderstorms; a significant variation in both wind speed and direction within the thunderstorm or air mass; and plenty of space for the rotation to develop.
That need for wide, open spaces is why you hear about tornadoes so much in the plain states and flat areas of the Midwest and West. Tornadoes are unusual in large cities and mountainous areas because they lack the open space needed for the tornado to develop.
However, it’s not impossible for tornadoes to form around cities. On May 12, 1997, a tornado struck very near downtown Miami, Florida, and lasted about 15 minutes. A number of people were injured and it caused $525,000 in damages. That tornado developed over open water, which provided the space for it to grow, and then move onshore. Plus, Oklahoma City alone has been hit by more than 100 tornadoes thanks to its flat surroundings.
How to Predict a Tornado
Unlike hurricanes or other severe weather events, tornadoes are hard to predict almost up until they hit, but there are still signs of impending twisters that you can look out for:
- A pale green sky is an indicator that a tornado may occur. Although no one knows why this is, some people theorize that because tornadoes usually form in the afternoon, the longer red and yellow wavelengths of afternoon sunlight turn water-heavy, bluish clouds to green.
- The Federal Emergency Management Agency (FEMA) also advises to look out for the following danger signs: large hail; dark, low-lying clouds; and a loud roar, similar to that of a freight train.
What Tornado Warnings Mean
- A tornado watch indicates possible tornadoes in your area. Stay tuned to the radio or television news.
- A tornado warning means that a tornado is on the ground or has been detected by Doppler radar. Seek shelter immediately!
How to Survive a Tornado
- If you are indoors, take cover in the cellar or a small space (a closet or bathroom) in the interior of your home. If you can’t decide where to go, choose the bathroom. The bathtub is a good, solid structure to hunker down in.
- Stay away from windows!
- If you are outdoors, find a field or ditch away from items that can fly through the air. Lie down as flat as you can.
- Do not stay in a car or try to drive away from a tornado. Cars can be flung about by high winds or crushed by debris.
- If you have evacuated your home, do not return until it is deemed safe to do so by local officials.