Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Every state is at some risk from this hazard.
The following are facts about tornadoes:
They may strike quickly, with little or no warning.
They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.
The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.
Tornadoes can accompany tropical storms and hurricanes as they move onto land.
Waterspouts are tornadoes that form over water.
Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.
Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.
Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.
Prevention and practice before the storm:
At home, have a family tornado plan in place, based on the kind of dwelling you live in and the safety tips below. Know where you can take shelter in a matter of seconds, and practice a family tornado drill at least once a year. Have a pre-determined place to meet after a disaster.
Flying debris is the greatest danger in tornadoes; so store protective coverings (e.g., mattress, sleeping bags, thick blankets, etc. in or next to your shelter space, ready to use on a few seconds' notice.
Turn on local TV, radio or NOAA Weather Radio and stay alert for warnings.
Forget about the old notion of opening windows to equalize pressure; the tornado will blast open the windows for you!
Know the signs of a tornado: Weather forecasting science is not perfect and some tornadoes do occur without a tornado warning. There is no substitute for staying alert to the sky. Besides an obviously visible tornado, here are some things to look and listen for:
1. Strong, persistent rotation in the cloud base.
2. Whirling dust or debris on the ground under a cloud base -- tornadoes sometimes have no funnel!
3. Hail or heavy rain followed by either dead calm or a fast, intense wind shift. Many tornadoes are wrapped in heavy precipitation and can't be seen.
4. Day or night - Loud, continuous roar or rumble, which doesn't fade in a few seconds like thunder.
5. Night - Small, bright, blue-green to white flashes at ground level near a thunderstorm (as opposed to silvery lightning up in the clouds). These mean power lines are being snapped by very strong wind, maybe a tornado.
6. Night - Persistent lowering from the cloud base, illuminated or silhouetted by lightning -- especially if it is on the ground or there is a blue-green-white power flash underneath.
During the Storm:
In a house with a basement:
Avoid windows. Get in the basement and under some kind of sturdy protection (heavy table or work bench), or cover yourself with a mattress or sleeping bag.
Know where very heavy objects rest on the floor above (pianos, refrigerators, waterbeds, etc.) and do not go under them. They may fall down through a weakened floor and crush you.
In a house with no basement, a dorm, or an apartment:
Avoid windows. Go to the lowest floor, small center room (like a bathroom or closet), under a stairwell, or in an interior hallway with no windows.
Crouch as low as possible to the floor, facing down; and cover your head with your hands.
A bath tub may offer a shell of partial protection. Even in an interior room, you should cover yourself with some sort of thick padding (mattress, blankets, etc.), to protect against falling debris in case the roof and ceiling fail.
In a mobile home:
Get out! Even if your home is tied down, you are probably safer outside, even if the only alternative is to seek shelter out in the open. Most tornadoes can destroy even tied-down mobile homes; and it is best not to play the low odds that yours will make it.
If your community has a tornado shelter, go there fast. If there is a sturdy permanent building within easy running distance, seek shelter there.
Otherwise, lie flat on low ground away from your home, protecting your head. If possible, use open ground away from trees and cars, which can be blown onto you.
In a car or truck:
Vehicles are extremely dangerous in a tornado. If the tornado is visible, far away, and the traffic is light, you may be able to drive out of its path by moving at right angles to the tornado.
Otherwise, park the car as quickly and safely as possible. Get out and seek shelter in a sturdy building.
If in the open country, run to low ground away from any cars (which may roll over on you). Lie flat and face-down, protecting the back of your head with your arms. Avoid seeking shelter under bridges, which can create deadly traffic hazards while offering little protection against flying debris.
In the open outdoors:
If possible, seek shelter in a sturdy building. If not, lie flat and face-down on low ground, protecting the back of your head with your arms.
Get as far away from trees and cars as you can; they may be blown onto you in a tornado.
After the Storm:
Keep your family together and wait for emergency personnel to arrive. Carefully render aid to those who are injured.
Stay away from power lines and puddles with wires in them; they may still be carrying electricity!
Watch your step to avoid broken glass, nails, and other sharp objects. Stay out of any heavily damaged houses or buildings; they could collapse at any time.
Do not use matches or lighters, in case of leaking natural gas pipes or fuel tanks nearby.
Remain calm and alert, and listen for information and instructions from emergency crews or local officials.
Enhanced Fujita Scale for Tornado Damage
An update to the original Fujita scale by a team of meteorologists and wind engineers, to be implemented in the U.S. on 1 February 2007.
*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage. These estimates vary with height and exposure.
This and more information can be found at the Storm Prediction Center website www.spc.noaa.gov