Updated:
January 23, 2008 16:15  

One of nature’s most powerful forces is a tornado. Check out this Q&A to be smart when tornadoes twist your way.

What is a tornado?

A tornado is a violent column of rotating air that comes down from a thunderstorm to reach the ground. Tornadoes usually last only a few minutes, but they can cause much damage as they travel along the ground. Some tornadoes can travel for many dozens of miles; other tornadoes may appear to skip above the ground for a few moments. Most tornadoes in Florida occur in June, July and August. However, the strongest tornadoes in Florida usually occur in February, March and April

Where do tornadoes come from?

Tornadoes develop within very strong thunderstorms called supercell thunderstorms. Supercell thunderstorms depend on air moving upward in a spiral. This rotating, rising air allows thunderstorms to BY JoN riZZo Weather Report Staff Writer Know the answers to stay safein a tornado Tornadoes last for several hours. They also may travel for 50 miles or more. Some supercell thunderstorms may produce several tornadoes.

Some weaker tornadoes have formed from regular thunderstorms. These tornadoes can occur when cold air rushing out from underneath one thunderstorm collides with cold air rushing out from another thunderstorm. As these winds merge from different directions, rotation takes place, and that rotation sometimes produces a tornado.

Tornadoes also can occur near the edge of tropical cyclones. They occur in squalls called rainbands. These tornadoes often occur more than 100 miles from the center of the tropical cyclone. Such tornadoes can strike with little warning.

How do we know the strength of tornadoes?

National Weather Service meteorologists use the Enhanced Fujita Scale, or EF Scale, to rate the strength of tornadoes. The EF Scale replaced the older Fujita Scale in 2007. Professor Theodore Fujita created the original scale in 1971. It helped meteorologists estimate the strength of the winds inside tornadoes. The scale is used when meteorologists investigate the damage caused by tornadoes.
The new EF Scale includes work both by meteorologists and wind engineers. Meteorologists first look at the tornado damage. Next, they compare the damage for a single type of home, business or other structure to the EF Scale. Finally, they estimate the wind speed that would have been needed to cause the damage. The EF Scale shows some major damage can occur in only 100-miles per hour (mph) winds.

On Feb. 2, 2007, three tornadoes moved through Central Florida during the early morning hours. Two of the tornadoes were rated EF-3. Those tornadoes heavily damaged hundred of homes and killed 21 people.

What is a waterspout?

A waterspout is a tornado over water. Some waterspouts occur from supercell thunderstorms.
Most waterspouts, however, occur from cloud lines. These are lines of tall, puffy cumulus clouds that occur along the shore or over the Florida Keys. Dr. Joseph Golden studied waterspouts in Florida for more than 35 years. He estimated that more than 300 waterspouts occur each year along the Florida coast. Most of these are weak. A few waterspouts do move ashore. Waterspouts that reach the shore can cause the same damage as a tornado.

When do tornado warnings occur?

The National Weather Service uses tools and volunteers to watch for severe weather. Skywarn Severe Weather Spotters are volunteers who report tornadoes to the National Weather Service. Doppler radar is used to look for thunderstorms, which may cause a tornado.

The National Weather Service will issue a tornado warning when a tornado is either seen by a severe weather spotter or indicated by Doppler radar. You and your family need to take cover right away whenever a tornado warning is issued for your area. Never try to outrun a tornado in a car. Seek shelter in a small room on the lowest floor of your home. Leave mobile homes and find a stronger building or house. Stay away from windows and doors. Use pillows to cover your head.

NOAA Alert Radio is the best way to stay informed about tornadoes. These are special radios that receive weather information. The NOAA Alert Radio will turn on and alert you of dangerous weather. It is very important to make sure the radio is always plugged in. Make sure it has a strong battery in case the power goes out.

How Does the Enhanced FUJITA Scale Work?

The Enhanced Fujita Scale (EF Scale) uses actual damage to estimate a tornado’s wind speed. Tornadoes are classified according to the damage they cause, on the Fujita Scale. This scale was named after its creator, Dr. Theodore Fujita. The EF Scale is to be used with caution. Tornado wind speeds are still largely unknown, and the wind speeds on the EF Scale never have been scientifically tested and proven. Winds of different speeds may cause the same damage depending on how well-built a structure is, wind direction, wind duration, battering by flying debris and various other factors.

The Enhanced Fujita Scale (EF-Scale) replaced the Fujita Scale (F-Scale) on February 1, 2007.

The original Fujita Scale (F-Scale), created by meteorology professor Doctor Theodore Fujita, was used by the National Weather Service from 1971 to 2006 to rate the strength of tornadoes. His scale used tornado damage to estimate tornado wind speeds. However, Dr. Fujita's scale did not consider how well a structure was built or flying debris around the tornado. As a result, some tornado wind speeds were reported higher than they actually were.

The Enhanced F-Scale (EF-Scale) was created by meteorologists and wind engineers to make estimating tornado winds more accurate. The EF-Scale looks at 28 different types of wind damage to trees, homes, power lines, businesses and skyscrapers. The original F-Scale did not take all of these details into account.

The EF-Scale will usually result in a lower wind speed than the F-Scale if the damage is similar. For example, an EF-Scale F3 tornado would have wind speeds between 136 and 165 miles per hour (mph), while the old F-Scale F3 tornado would have wind speeds between 162 and 209 mph. The wind speeds needed to cause F3 damage are not as high as once thought. More information can be found at http://www.spc.noaa.gov/faq/tornado/ef-scale.html.

The No. 1 Wind Safety Rule

The No. 1 wind safety rule is to get as many walls between you and the outside world as possible so the debris in the wind cannot reach you. It is not the wind that kills and injures people; it is the debris in the wind. For example, you can drive on the highway at 70 mph and stick your hand out the window and not be harmed. However, you would suffer serious injury if your hand hit a brick or branch while the car is speeding down the road. If you can keep the debris in the wind from reaching your location, you will survive the wind event–whether it is a tornado, hurricane or thunderstorm downburst wind.