Tornadoes

United States Search and Rescue Task Force

One of the most destructive natural phenomena, tornadoes are swirling winds that spin at phenomenal speeds of up to 400 mph.  Like hurricanes, they are caused by severe low pressure zones that attract winds with force.  They have relatively small bases, a fact which greatly magnifies their destructive power.  Tornadoes are difficult to predict and often strike without warning.  Meteorologists expect to be able to predict a tornado in the near future.  

Tornadoes may range in width from several hundred yards to more than one mile across.  Although tornadoes occur throughout most of the United States, areas in the Midwest and South are particularly susceptible to tornado activity. 

When a tornado is coming, you have only a short amount of time to make life-or-death decisions.  Advance planning and quick response are the keys to surviving a tornado.

Waterspout – 

Waterspouts are tornadoes over water which draw up large columns of water.  If a waterspout moves from sea to shore, expect fish and other sea creatures to rain down!

BEFORE

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

Have disaster supplies on hand.

• Flashlight and extra batteries
• Portable, battery-operated radio and extra batteries
• First aid kit and manual
• Emergency food and water
• Nonelectric can opener
• Essential medicines
• Cash and credit cards
• Sturdy shoes

Develop an emergency communication plan.

In case family members are separated from one another during a tornado (a real possibility during the day when adults are at work and children are at school), have a plan for getting back together.

Ask an out-of-state relative or friend to serve as the “family contact.” After a disaster, it's often easier to call long distance. Make sure everyone in the family knows the name, address, and phone number of the contact person.

Tornado Watches and Warnings

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

A tornado warning is issued when a tornado has been sighted or indicated by weather radar.

Mobile Homes

Mobile homes are particularly vulnerable. A mobile home can overturn very easily even if precautions have been taken to tie down the unit. When a tornado warning is issued, take shelter in a building with a strong foundation.If shelter is not available, lie in ditch or low-lying area a safe distance away from the unit.

Tornado Danger Signs

Learn these tornado danger signs:

• An approaching cloud of debris can mark the location of a tornado even if a funnel is not visible.
• Before a tornado hits, the wind may die down and the air may become very still.
• Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

DURING

If at home:

• Go at once to the basement, storm cellar, or the lowest level of the building.
• If there is no basement, go to an inner hallway or a smaller inner room without windows, such as a bathroom or closet.
• Get away from the windows.
• Go 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 or desk and hold on to it.
• Use arms to protect head and neck.
• If in a mobile home, get out and find shelter elsewhere.

If at work or school:

• Go to the basement or to an inside hallway at the lowest level.
• Avoid places with wide-span roofs such as auditoriums, cafeterias, large hallways, or shopping malls.
• Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it.
• Use arms to protect head and neck.

If outdoors:

• If possible, get inside a building.
• If shelter is not available or there is no time to get indoors, lie in a ditch or low-lying area or crouch near a strong building. Be aware of the potential for flooding.
• Use arms to protect head and neck.

If in a car:

• Never try to outdrive a tornado in a car or truck. Tornadoes can change direction quickly and can lift up a car or truck and toss it through the air.
• Get out of the car immediately and take shelter in a nearby building.
• If there is no time to get indoors, get out of the car and lie in a ditch or low-lying area away from the vehicle. Be aware of the potential for flooding.

AFTER

• Help injured or trapped persons
• Give first aid when appropriate. Don't try to move the seriously injured unless they are in immediate danger of further injury. Call for help.
• Turn on radio or television to get the latest emergency information.
• Stay out of damaged buildings. Return home only when authorities say it is safe.
• Use the telephone only for emergency calls.
• Clean up spilled medicines, bleaches, or gasoline or other flammable liquids immediately. Leave the buildings if you smell gas or chemical fumes.
• Take pictures of the damage–both to the house and its contents–for insurance purposes.
• Remember to help your neighbors who may require special assistance–infants, the elderly, and people with disabilities.

INSPECTING UTILITIES IN A DAMAGED HOME

Check for gas leaks–If you smell gas or hear a blowing or hissing noise, open a window and quickly leave the building. Turn off the gas at the outside main valve if you can and call the gas company from a neighbor's home. If you turn off the gas for any reason, it must be turned back on by a professional.

Look for electrical system damage–If you see sparks or broken or frayed wires, or if you smell hot insulation, turn off the electricity at the main fuse box or circuit breaker. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice.

Check for sewage and water lines damage–If you suspect sewage lines are damaged, avoid using toilets and call a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap. You can obtain safe water by melting ice cubes.

MITIGATION

Mitigation includes any activities that prevent an emergency, reduce the chance of an emergency happening, or lessen the damaging effects of unavoidable emergencies.  Investing in preventive mitigation steps now, such as checking local building codes and ordinances about wind-resistant designs and strengthening unreinforced masonry, will help reduce the impact of tornadoes in the future.  For more information on mitigation, contact your local emergency management office.

Fujita – Pearson Tornado Scale

Tornadoes are classified using the Fujita Wind Damage Scale.  This scale correlates damage with windspeed, as shown in the diagram and chart below.

F-0: 40-72 mph, chimney damage, tree branches broken
F-1: 73-112 mph, mobile homes pushed off foundation or overturned
F-2: 113-157 mph, considerable damage, mobile homes demolished, trees uprooted
F-3: 158-205 mph, roofs and walls torn down, trains overturned, cars thrown
F-4: 207-260 mph, well-constructed walls leveled
F-5: 261-318 mph, homes lifted off foundation and carried considerable distances, autos thrown as far as 100 meters

Information and Facts

Deadly tornadoes seem to have stimulated people's interest in storm shelters.

One of the very first things you should do if you are thinking about a storm shelter is to determine the actual risk in your area.   This has been made much easier with a new publication by the Federal Emergency Management Agency and the Wind Engineering Research Center at Texas Tech University, using data from the SPC.  We are excerpting three illustrations here.

Figure 1.1 shows the number of recorded tornadoes per 1,000 square miles.

Figure 1.2 shows the wind zones throughout the US.

By using both maps and the table below, you can figure out whether your risk is considered low, moderate, or high!