TPEMA Tornado Info

Tornados

[ Facts & Myths | Preparation | Watch/Warning | What To Do | Fujita Scale ]

Tornado Facts

A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is usually spawned by a thunderstorm 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 windblown debris. The U.S. has the highest incidence of tornados worldwide, with about 1,000 occurring every year. Tornados can come one at a time or in clusters, and they can vary greatly in length, width, direction of travel, and speed. They can leave a path 50 yards or a mile wide. They may touch down for a matter of seconds, or remain in contact with the ground for over an hour.

Tornados are more prevalent from April through July, with May and June being the peak months in the U.S. However, tornados can form any time of the year.
They tend to occur in the afternoons and evenings: over 80 percent of all tornados strike between noon and midnight.
Tornados can and do occur in every state in the country.
They can be nearly invisible, marked only by swirling debris at the base of the funnel. Some are composed almost entirely of windblown dust and still others are composed of several mini-funnels.
Injuries or deaths related to tornados most often occur when buildings collapse, people are hit by flying objects or are caught trying to escape the tornado in car.
Sometimes just before a tornado hits, the sky is a dark or often greenish color. The wind may die down and the air may become eerily calm: in other cases they are preceded by strong winds.
The sound of a tornado has been described to that of a freight train or a jet engine, but most likely by the time you hear such a noise, it's too late.

Tornado Myths

Tornados are always visible from a great distance.
False! They can be hidden in heavy rainfall.
Tornados cause house to explode from changes in air pressure.
False! Homes are damaged by strong winds, not air pressure changes.
Tornados cannot cross water.
False! They can cross bodies of water such as rivers and lakes. Tornados formed on water are called "Waterspouts".
You can balance the pressure inside your home by opening windows, thereby preventing damage.
False! A tornado can rip through a structure, whether the windows are open or not.

Preparation

Conduct tornado drills

Designate an area in the home as a shelter, and practice having everyone in the family go there in response to a tornado threat.

Inventory your property

In case of tornado, flooding or other disaster, this inventory will be invaluable to you in settling your insurance claim. Make sure you keep your inventory in a safe place, like a bank safe deposit box.

Develop a Family Disaster Plan

A Family Disaster Plan Checklist is included on this page.

Learn how your community handles emergencies

Contact your local Emergency Management Agency.

Watches / Warnings

Tornado Watch

Issued by the National Weather Service when tornadoes are possible in your area. Remain alert for approaching storms. Remind family members where the safest place(s) within your home are located, and listen to the radio or television for further developments.

Tornado Warning

Issued when a tornado has been sighted or indicated by weather radar. If the warning is for your area and the sky becomes threatening, move to your pre-designated place of safety. Turn on a battery-operated radio and wait for further instructions.

Warning! What To Do

Home / Apartment

Seek shelter in the lowest level of your home. If there is no basement, go to an inner hallway, or a smaller inner room without windows, such as a bathroom or closet. Keep away from all windows.
For added protection, get under something strong, such as a workbench or heavy table.
Cover your body with a blanket or sleeping bag.
Take your car keys; should a tornado hit your area, your car may be operable, but keys would be lost in the rubble.
Collect your Family Disaster Supplies Kit and keep it with you.
Keep your pet on a leash or in a carrier.
Get storm updates from The Weather Channel, your local TV or radio station, or NOAA Weather Radio.
Stay indoors until officials say it is safe.

Work or School

Go to the basement or to an inside hallway at the lowest level. Keep away from all windows.
Avoid places with wide-span roofs such as gymnasiums, auditoriums, cafeterias, large hallways or shopping malls.
Use your arms to protect your head and neck.

Mobile Homes

Leave immediately and take shelter inside a building.
Seek shelter on foot if possible. DO NOT DRIVE YOUR CAR! Do not get under a mobile home.
If shelter is not available, lie in a ditch, ravine, culvert or low-lying area away from the unit.
Use your arms or a piece of clothing to protect your head and neck.
Plan ahead. Make arrangements with friends or neighbors that have basements. If the weather looks threatening, go there.
Encourage your mobile home group to develop it's own shelter.

Outside

Try to get inside and seek out a small, protected space with no windows.
If shelter is not available, lie in a ditch, ravine, culvert or low-lying area.
Use your arms or a piece of clothing to protect your head and neck.
Do not get into a grove of trees.

Motor Vehicles

NEVER try to outdrive a tornado. Tornados can change direction quickly and can lift up a car or truck and toss it through the air.
Stop immediately, get out and take shelter in a nearby building.
If shelter is not available, lie in a ditch, ravine, culvert or low-lying area away from the vehicle.
Use your arms or a piece of clothing to protect your head and neck.
Do not get under or next to your vehicle; it may roll over on you.

THERE IS NO GUARANTEED SAFE PLACE
DURING A TORNADO. DO NOT WATCH
THE TORNADO.

WHEN THE SIRENS GO OFF, DO NOT RUN
OUTSIDE TO SEE WHAT IS HAPPENING.

THE SIREN MEANS YOU ARE IN IMMEDIATE
DANGER. SEEK SHELTER IMMEDIATELY.

YOUR LIFE AND THE LIVES OF THOSE AROUND
YOU MAY DEPEND ON YOUR ACTIONS.

The Fujita Scale

The Fujita Scale is used to rate the intensity of a tornado by examining the damage caused by the tornado after it has passed over a man-made structure.

F-Scale Intensity Phrase Wind Speed Type of Damage

F0 Gale
Tornado
40-72 mph Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.

F1 Moderate
Tornado
73-112 mph 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 roads; attached garages may be destroyed.

F2 Significant
Tornado
113-157 mph Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.

F3 Severe
Tornado
158-206 mph Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted.

F4 Devastating
Tornado
207-260 mph Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F5 Incredible
Tornado
261-318 mph Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-inforced concrete structures badly damaged.

F6 Inconceivable
Tornado
319-379 mph These winds are very unlikely. The small area of damage they might produce would probably not be recognizable along with the mess produced by F4 and F5 wind that would surround the F6 winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies.

Family Disaster Plan

Family Disaster Preparedness

Decide where to go if at home, school, work, outdoors, or in a car when a tornado or flood warning is issued.
Update these plans every school year and as places of employment and residence change.

Family Disaster Communication

Designate a friend or relative outside your town as your contact in the event you are separated from family members during a tornado or flood.
Agree upon a place where family members can meet if separated.

Family Disaster Supplies Kit

Essentials:
Battery-operated radio
Flashlight
Extra batteries
Water
High calorie, non-perishable food
First Aid kit (one for your home and one for each car)
Prescription and non-prescription drugs
Tools and supplies (paper cups, utility knife, hammer, matches, etc.)
Supplies to maintain sanitation (toilet paper, paper towels, household chlorine bleach)
Clothing and bedding
Necessities for baby
Necessities for pet
Important family documents
Entertainment (games and books)

Non-perishable contents should be changed or replaced every six months.

Family Pet Care

Keep in mind that most shelters do not accept pets.
Contact your local Emergency Management agency for information on how to care for your pet during a weather emergency.

F-Scale	Intensity Phrase	Wind Speed	Type of Damage
F0	Gale Tornado	40-72 mph	Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.
F1	Moderate Tornado	73-112 mph	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 roads; attached garages may be destroyed.
F2	Significant Tornado	113-157 mph	Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.
F3	Severe Tornado	158-206 mph	Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted.
F4	Devastating Tornado	207-260 mph	Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.
F5	Incredible Tornado	261-318 mph	Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-inforced concrete structures badly damaged.
F6	Inconceivable Tornado	319-379 mph	These winds are very unlikely. The small area of damage they might produce would probably not be recognizable along with the mess produced by F4 and F5 wind that would surround the F6 winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies.