"Killer Twisters Claim 43 Along Tornado Alley," newspaper headlines exclaimed on May 9, 1999. Just the evening before, a powerful tornado packing winds of more than 260 miles per hour ripped a swath a mile wide through Oklahoma City and its suburbs, chewing up homes and trucks in its path.

The deadliest tornadoes to strike Oklahoma in more than 50 years, these forceful twisters served as a fresh reminder of the wonderful, horrible power of nature.

It also serves as a warning for the rest of us of the need to prepare against nature's grandest atmospheric force, the tornado. At their greatest strength, twisters can approach speeds of 320 miles per hour - enough power to level the best-constructed brick walls, rip large homes from their foundations and up into the air, and throw tractor-trailers a distance of about 300 feet.

The greatest and most frequent tornado occurrences happen in the United States. Tornadoes can in fact form in any state, but they occur most frequently in Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Louisiana, Mississippi, Missouri, Nebraska, Oklahoma, South Dakota, and Texas.

Whether you live in this group of states - often called "Tornado Alley" - or not, spring brings the increased possibility of a deadly tornado. Are you prepared?

Secrets of Survival will help you learn about the atmospheric events that signal the possibility of a tornado, and what safety measures you can take to survive if a twister hits.

'The Finger of God'

The National Weather Service defines a tornado as "a violently rotating column of air pendant from a thunderstorm cloud and touching the ground."

The Federal Emergency Management Agency (FEMA) has a longer but much clearer definition:

A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is spawned by a thunderstorm (or sometimes as a result of a hurricane) and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly. The damage from a tornado is a result of the high wind velocity and wind-blown debris. Tornado season is generally March through August, although tornadoes can occur at any time of year. They tend to occur in the afternoons and evenings: over 80 percent of all tornadoes strike between noon and midnight.

Each year, about 100,000 thunderstorms form over the United States. Between 600 and 1,000 of those thunderstorms will give birth to tornadoes.

Some may also remember the now famous quote from the film 'Twister', when a character asked a group of meteorologists following a series of tornadoes - "storm chasers" - how they would define the strongest twisters. After a moment of silence, one of them replies with a depth of feeling approaching awe that such an event is "the finger of God."

That's a high statement. But there's something about the greatest tornadoes that makes the highness hard to dismiss.

Some quick facts:

*Tornadoes are the most destructive of all weather-related events, and produce the most violent winds on earth. Winds inside the greatest twisters can swirl well over 300 mph.

*Tornadoes can be nearly invisible, marked only by swirling debris at the base of the funnel. Some are composed almost entirely of windblown dust; others can be composed of several mini-funnels.

*Twisters can reach heights of 60,000 feet into the atmosphere.

*On average, during a tornado's 'path' - the total area certain to suffer at least some destruction by its deadly force - the twister will travel about 4 miles on the ground and cut a swath about 400 yards wide; but the worst ones can travel for 100 miles and be as large as a mile wide.

*The average tornado travels along the ground at a speed of 25 to 40 mph., but can go from one place to the next at speeds of up to 70 mph.

*Twisters stay on the ground for an average of four to five minutes; however, a tornado can touch down several times.

*Most tornadoes move from southwest to northeast.

*Most twisters in the Northern Hemisphere rotate in a counter-clockwise direction. Most in the Southern Hemisphere rotate in a clockwise direction.

*Building damage during a tornado happens when high winds cause a buildup of pressure on building surfaces. This pressure is wind velocity squared.

*Most tornadoes occur between 3 pm and 7 pm

*Tornadoes occur throughout the world; however, the greatest number and most intense, deadly tornadoes occur in the United States.

*About 800 tornadoes touch down in the United States each year.

*Half of all tornadoes occur during the spring months of April, May, and June.

*Only 2 percent of tornadoes are considered violent, but those storms cause 70 percent of tornado-related deaths.

*In November 1988, a rash of 121 tornadoes struck 15 south central states, resulting in 14 lives lost and damages reaching $108 million.

*According to the National Weather Service, about 42 people are killed because of tornadoes each year.

Luckily, we are not mere sitting ducks, even against something as powerful and unpredictable as a twister. Every year, scientists and meteorologists are learning more about the formation and behavior of the mighty winds. This has resulted in quicker and more reliable emergency broadcasts accurately predicting where a tornado will appear and its probable path.

For instance, the quick reports of twisters possibly headed into the heart of Oklahoma City in May of '99 certainly saved many lives. Those reports were only possible because of what had been learned about twisters in the early and mid-90s.

Also, the fact that tornadoes usually strike between 3-7 pm gives us a fairly certain time frame in which to look out for them, and ensures us that most people will be awake and will probably hear reports immediately if a dangerous situation arises.

And in the US, if a situation begins as we're outside away from a radio or TV or when we're asleep, the National Oceanic and Atmospheric Administration (NOAA) weather alert radio receiver - equipped with the famous warning siren - can warn of an impending tornado if people are away from the usual immediate sources.

The Fujita - Pearson (FPP) Tornado Scale

Shortly, this is a system of estimating and reporting both tornadic wind intensity, devised by Professor T. Theodore Fujita (1920-1998), and path length and width by Allen Pearson in 1971. It was quickly taken up as the best means to rate a twister's destructive capacity. The scale is based on the damage a tornado causes on man-made structures.

According to Fujita and Pearson, the size of a tornado's funnel is not an indication of its intensity. The Fujita Scale is therefore based on damage, not the appearance of the funnel.

*F0 - Gale Tornado 40-72 mph

Path length 0.3-0.9 miles; path width 6-17 yards

Light damage; Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.

F1 - Moderate Tornado (73 - 112 mph)

Path length: 1.0-3.1 miles; path width: 18-55 yards

Moderate damage; The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the road; attached garages may be destroyed.

F2 - Significant Tornado (113 - 157 mph)

Path length: 3.2-9.9 miles; path width: 56-175 yards

Considerable damage; entire roofs torn from frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light-object missiles generated.

F3 - Severe Tornado (158 - 206 mph)

Path length: 10-31 miles; path width: 176-566 yards

Severe damage; walls torn from well-constructed houses; trains overturned; most trees in forests uprooted; heavy cars lifted off ground and thrown.

F4 - Devastating Tornado (207 - 260 mph) Path length: 32-99 miles; path width: 0.3-0.9 miles

Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F5 - Incredible Tornado (261 - 318 mph) Path length: 100-315 miles; path width: 1.0-3.1 miles

Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile-sized missiles fly through the air 100 yards or more; trees debarked; steel reinforced concrete structures badly damaged.

Since we are going on about the awesome power that a tornado can bring, we at Secrets of Survival should definitely live up to our name and remind our readers that under no circumstances should they ever attempt to follow or chase a twister down. They are, for all practical purposes, still quite unpredictable, and may surge with far greater strength, disappear and reappear, or change direction at a moment's notice.

We are a survival site, and so the very best advice we can give is to let the storm chasing to those who are either sufficiently trained, or simply stupid enough, to follow one of these things. You're not actors on a movie set; there is no take two in real-life. Your only worry should be to protect yourself, those you care for, and your home as best you can. How do you do that?

Protecting Yourself Against the Twister

Many thanks here to both the Federal Emergency Management Agency (FEMA) and the Illinois Emergency Management Agency (IEMA) for their detailed information on how one can best prepare for a twister - before it hits, as it's sweeping over you, and immediately after the event.

Many may suppose that they need only worry about the funnel cloud as it sweeps over them; but without the right preparations beforehand or maintaining the correct behavior afterward, a person could still easily end up becoming one of those injured, if not worse. Avoid such problems by knowing what to do before it happens.

Before a Tornado

The best precautions before a twister hits:

Determine the best location in both your home and place of employment in which to seek shelter when threatened by a tornado. A basement or cellar will usually afford the best protection. If an underground shelter is not available, identify an interior room or hallway on the lowest floor.

Conduct periodic tornado safety drills with your family.

Especially if you live in 'tornado alley', you should know the locations of designated shelters in places where you and your family spend time, such as public buildings, nursing homes and shopping centers. Ask whether your children's' schools have identified shelter space.

Have emergency supplies on hand.

Learn how to shut off the utilities to your home.

Decide how and when your family will reunite, if separated.

Make an inventory of your possessions. Take photographs of or videotape your belongings. Keep records in a safe deposit box or some other safe place away from the premises.

Here's an idea; purchase a National Oceanic and Atmospheric Administration (NOAA) Weather Radio with battery backup and tone-alert feature which automatically alerts you when a Watch or Warning is issued. Or simply purchase a battery-powered commercial radio, and extra batteries. Whichever you use, make sure from time to time that you know where the radio is, that it still works, and that all the batteries are still good.

Make sure you know the names of the towns and counties in which you live, work and haunt. They are used during both tornado warnings and watches to identify the area of potential tornadoes; therefore a solid knowledge here is essential. Keep a good, easy-to-read map in your car if you travel frequently, one that clearly details names of counties - which authorities use as the principal markers in spotting tornado activity - as well as towns.

Also, remember the terms used to describe tornado threats: Tornado Watch and Tornado Warning. What's the difference?

A tornado watch is issued by the National Weather Service when tornadoes are possible in your area. Remain alert for approaching storms. This is the time to remind family members where the safest places within your home are located.

During a tornado watch, observe the sky and listen to radio or television for more information. Be prepared to take shelter. If you see any revolving funnel-shaped clouds, report them immediately by telephone to your local law enforcement agency. If they appear to be headed your way, seek shelter in a well-constructed, sturdy building or structure as soon as possible.

For some reason, God seems to hate mobile homes. In all honesty though, if you do live in a mobile home, this is the time to temporarily move to a more substantial structure. Many advise either moving to such a location or going outside, lying down in a 'low-lying area' and waiting for the 'Finger of God' to strike only after tornadoes begin appearing around your location. But to us here at Secrets of Survival, that smacks of last-minute desperation.

Besides, we never much cared for lying in ditches anyway - not if we could ever avoid it, ant any rate. Don't wait till the last minute. Make sure you, and those you care for, are protected. If you live in a mobile home, move to a more substantial structure during a tornado watch and stay there until the watch has passed.

A tornado warning however is issued when a tornado has been actually sighted or indicated by weather radar. During a tornado warning, everyone should take shelter, turn on a battery-operated radio or television, and wait for the "all clear" announcement by authorities.

If you've heard there's a tornado warning in your area, call your local emergency management office or American Red Cross chapter about it if you care to know more. Also ask about community warning signals.

If there's one thing we can't stress enough, it's that you need to have your wits about you, and use all your senses in determining any danger. If you know there's a tornado warning in your area and the skies around you look particularly dark, or there seems to have been a sudden drop in barometric pressure, seek shelter immediately. Take along at least a radio (any one will do but an NOAA radio would admittedly be best) and some water if you can.

Watch for any unusual behavior out of animals: does your dog or cat seem particularly anxious? Does there seem to be a sudden drop of birds in your area, especially since the skies have become darker or the pressure has fallen? That may also be a good indication that a twister is about to appear in your immediate area. Seek shelter when you can, taking with you the things mentioned above.

If there's one constant with a twister, it's the sound that accompanies the tornado: it has most often been described as a deep rumble that builds into a roar.

Even if there hasn't been a tornado watch called in your area, if there is at least a tornado warning in your county or if the skies seem particularly ominous and the air possesses that drop in air pressure, and you begin to hear such a steady sound, seek shelter immediately. Unless you live next to a train station or airport runway (the sound of a twister has been compared to the long, low rumble of a speeding train more than anything else), you should not be hearing such a sound.

Don't bother to go outside and investigate; it may be too late for that. The suddenness with which a twister can attack deserves special consideration when we know there's such a weather problem anywhere in our immediate area.

The simplest advice? Be ready to take shelter if and when the need calls for it.

During a Tornado

When a tornado has been sighted in your immediate area take the following actions:

At Home

Go at once to your predetermined shelter (the basement, storm cellar, or the lowest level of the building). Stay there until the danger has passed.

If there is no basement, go to an inner hallway or a small inner room without windows, such as a bathroom or closet.

However much you want to see the storm, stay away from all windows, doors, and outside walls.

Go directly to the center of the room. Stay away from corners because they tend to attract debris. Get under a piece of sturdy furniture such as a workbench or heavy table and hold on to it for all you're worth.

Use sofa cushions or your arms to protect your head and neck.

If in a mobile home, get out and seek shelter elsewhere. A mobile home can overturn very easily even if precautions have been taken to tie down the unit. If there isn't a substantial shelter nearby, seek shelter in a low-lying area. Use your arms to protect your head and neck.

In a Public Building (School, Hospital, Factory, Shopping Center, etc.)

Go to the basement or to an inside hallway, a small, interior room, or a bathroom or closet on the lowest possible level.

Avoid places with wide-span roofs such as auditoriums, cafeterias, gymnasiums, and large hallways.

Stay away from windows and open spaces.

Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it.

Outdoors

If possible, get inside a substantial building.

If shelter is not available or there is no time to get indoors, lie in a ditch, culvert, or low-lying area or crouch near a strong building. Use your arms to protect your head and neck. Be alert for potential flash flooding.

In A Vehicle

Never try to outrun a tornado in a vehicle. Heavy rain, hail, and traffic may impede your movement, and tornadoes can travel as quickly as 70mph over dry land. Tornadoes can quickly change directions, and can easily lift up a vehicle and toss it through the air.

Pull to the side of the road avoiding trees, power lines and other objects that could fall or be hazardous.

Get out of the vehicle immediately and try to take shelter in a nearby building.

If there isn't time to get indoors, get out of the vehicle and lie in a ditch, culvert, or low-lying area away from the vehicle. Use your arms to protect your head and neck.

After a Tornado

Monitor the radio or television for emergency information or instructions.

Check for injured victims. Render first aid if necessary.

Do not attempt to move severely injured victims unless absolutely necessary. Wait for emergency medical assistance to arrive.

Look out for broken glass and downed power lines.

Use the telephone only for emergency calls.

Try to get out of damaged buildings. Once out, do not reenter unless it's absolutely necessary. Use great caution at all times.

Take photos or videotape the damage to your home or property.

If driving, be alert for hazards in the roadway.

Check on neighbors/relatives who may require special assistance.

If unaffected by the tornado, stay out of the damaged area until allowed in by officials; your presence may hamper emergency operations.

The Most Important Reminders

1.The best protection during a tornado is in an interior room on the lowest level of a building, preferably a safe room.

2.Tornadoes strike with incredible velocity. Wind speeds may approach 320 miles per hour. These winds can uproot trees and structures and turn harmless objects into deadly missiles, all in a matter of seconds. Mobile homes are particularly vulnerable to tornadoes.

3.Injury or deaths related to tornadoes most often occur when buildings collapse, people are hit by flying objects or are caught trying to escape the tornado in a car.

4.Tornadoes are most destructive when they touch ground. Normally a tornado will stay on the ground for no more than 20 minutes; however, one tornado can touch ground several times in different areas.

5.Tornadoes can occur practically anywhere, but are most prevalent in the US, and are most frequent in the Midwest, Southeast and Southwest. The states of Oklahoma, South Dakota, Missouri, Nebraska, Illinois, Indiana, Iowa, Kansas, Arkansas, Alabama, Florida, Georgia, Louisiana, Mississippi, and Texas are at greatest risk.

Raising Awareness

The media can raise awareness about tornadoes by providing important information to the community. A few quick suggestions:

1.Publish a special section in your local newspaper with emergency information about tornadoes. Localize the information by printing the phone numbers of local emergency services offices, the American Red Cross, and hospitals.

2.Periodically inform your community of local public warning systems.

3.Sponsor a "Helping Your Neighbor" program at your local schools to encourage children to think of those persons who require special assistance such as elderly people, infants, or people with disabilities.

4.Conduct a series on how to protect yourself during a tornado in case you are at home, in a car, at the office, or outside.

5.Interview local officials about what people living in mobile home parks should do if a tornado warning is issued.

Many homes in the US 'Deep South' are for some reason built without a basement - a fact that is particularly strange since so many southern states are part of 'tornado alley'. In apparent response to this, a word from FEMA:

FEMA is urging people who live in tornado-prone areas to make sure they have a tornado-safe place to go during a tornado. In the absence of a basement, a tornado-safe room build within the house will protect your family during a tornado. Properly built safe rooms can provide protection against winds of 250 miles per hour and against flying objects traveling at 100 miles per hour. The plans for the safe rooms were developed along with the Wind Engineering Research Center of Texas Tech University in Lubbock, Texas.