TORNADO SAFETY GUIDE MARCH 2012

Damage from a category F3 tornado, Mena, Arkansas, 09 April 2009

1st Heavy Brigade Combat Team Safety Office

CONTENTS

Tornadoes and Their Destructive Force

Warning Signs of a Tornado

Important Tornado Facts Separating Facts from Myths about Tornados Preparation for a Tornado Tornado Watches and Tornado Warnings What to do if a Tornado Approaches

The Safest Places to be in the Event of a Tornado

1

In the Midwest states, including Missouri. peak tornado occurrence is in mid-March through late-June. But tornado season is generally considered to be March through September. Tornadoes have occurred in Missouri in every month of the year. Missouri is considered at high risk from tornadoes and is in “tornado alley,” which places the state in the top five for tornado activity. Tornadoes and Their Destructive Force

A tornado is defined as a violently rotating column of air extending from a thunderstorm to the ground. 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.

Essentially, tornadoes are a vortex storm with two components of winds. The first is the rotational winds that can measure up to 500 miles an hour, and the second is an uplifting current of great strength. The dynamic strength of both these currents can cause vacuums that can overpressure structures from the inside.

In an average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500 injuries. The most violent tornadoes are capable of tremendous destruction. Damage paths can be in excess of one mile wide and 50 miles long. Once a tornado in Broken Bow, Oklahoma, carried a motel sign 30 miles and dropped it in Arkansas!

The most deadly tornado in American history occurred on 18 March 1925, in Ellington, Missouri. The Tri-State Tornado went through parts of Missouri, Illinois, and Indiana and killed 685 persons, injuring 2027! The tornado traveled at an average speed of 62 MPH which is approximately double the speed of an average tornado. The wind speeds of the funnel were 261 to 318 MPH. It traveled a distance of 219 miles, destroyed 15,000 homes, and caused $16.5 million in property damage, which would be almost $2 billion in today’s dollars. In Oklahoma, on 03 May 1999, a tornado occurred with wind speeds estimated to be 318 MPH, believed to be the highest tornado wind speeds ever recorded.

With such destructive force involved, it is essential that we be prepared and take immediate action is a tornado approaches.

Photo of some of the damage caused by the F5 tornado in Moore, Oklahoma, 03 May 1999

2

Warning Signs of a Tornado

These are some things that can indicate that a tornado is imminent or may form soon:

Dark, often greenish sky Wall cloud* Large hail Hail or heavy rain followed by extreme shifts in wind Loud roar; similar to a freight train A loud, continuous rumble which doesn't fade over time A strong, continuous rotation in the clouds Whirling dust and/or debris on the ground beneath a layer of clouds Bright, blue-green flashes near the ground of power lines breaking Lowering of the clouds in a spiraling fashion Before a tornado strikes, the wind may die down and the air may become very still

* A wall could is an isolated cloud lowering attached to the rain-free base of the thunderstorm. The wall cloud is usually to the rear of the visible precipitation area. Wall clouds are about two miles in diameter and mark the area of strongest updraft in the storm.

Photo: A wall cloud with tail cloud

3

Important Tornado Facts

They may strike quickly, with little or no warning. Tornadoes are most likely to occur between 3 and 9 p.m. but have been known to occur at

all hours of the day or night. Peak tornado season in Missouri is mid-March through late-June. But tornado season is

generally considered to be March through September. Tornadoes have occurred in Missouri in every month of the year. Missouri is considered at high risk from tornadoes and is in “tornado alley,” which places the state in the top five for tornado activity.

The average tornado moves from Southwest to Northeast, but tornadoes have been known to move in any direction. The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.

Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible.

They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.

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

The Fujita Tornado damage scale is below, to help better explain the different categories of tornadoes. The larger the scale, the more damage can be done.

Category F0: Light damage with winds less than 73 mph; some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; signs damaged

Category F2: Considerable damage with winds between 113 and 157 mph; roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.

Category F3: Severe damage, with winds between 158 and 206 mph; roofs and some walls torn from well-constructed houses, trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.

Category F4: Devastating damage with winds between 207 and 260 mph; Well-constructed houses leveled; structure with weak foundations blown off some distance; cars thrown and large missiles generated.

Category F5: Incredible damage with winds between 261 and 318 mph; Strong frame houses lifted off foundations and swept away; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; incredible phenomena will occur.

4

Separating Facts from Myths About Tornados

Tornado Myth: Opening a window during a tornado will prevent a house from exploding.

Truth: It was believed that opening a window during a tornado would equalize the air pressure in a house but this has been proven to be not true.

Although it appears that a house has exploded due to a tornado, it really hasn’t. During a tornado, glass windows are the first to be broken by flying debris and wind force. When a strong wind enters a house, it forces the roof upwards and the walls fall outwards as a result of no structural support. Even with a window left open, the rapid attack of a tornado does not allow sufficient time for the air pressure to equalize anyway.

The experts recommend spending those precious moments seeking shelter when a tornado is approaching rather than opening the windows.

Tornado Myth: The southwest corner of a basement is the safest location during a

tornado.

Truth: It was believed that most tornadoes blow in from the southwest and the debris would be pushed to the opposite side of the basement. Although many tornadoes come from the southwest, they can change direction in an instant. Studies performed after a tornado have shown that a southwesterly tornado will shift a house to the northwest thus causing the southwest corner of a basement to collapse due to a sudden lack of structural support.

The best shelter in a building is in the middle of the basement because it is away from exterior walls. Hide under sturdy or protective objects such as the stairs, or workbench/heavy table or a mattress. The intent is to stay away from exterior walls and windows. Interior bathrooms or closets are considered safe places. This would also apply to non-basement homes. Keep covered in order to avoid flying debris.

Tornado Myth: Highway overpasses provide safe shelter from tornadoes.

Truth: Overpasses act as wind tunnels which increase the wind speed and should not be used as tornado shelters. A video sequence shot by a television crew who hid under an overpass during a weak tornado in Andover Kansas gave a false message about safety.

They were lucky because the full force of the tornado was not directly overhead and they able to hold on to exposed girders in a crawlspace. A lesser seen video is of a family who hid underneath an overpass and the mother lost her grip. She was killed when her body was blown half a mile down the highway. An overpass can be a very unsafe location to be in the event of a tornado. It can make you a stationary target in an open area, with virtually no protection. By climbing up under an overpass, people will be exposed to higher wind speeds and more flying debris.

If caught on the highway during an approaching tornado, get out of the vehicle and seek shelter in a ditch or a low-lying area, but away from the vehicle in case it flips over. The intent is to find the lowest area possible rather than seeking shelter above ground level.

5

Tornado Myth: A car can outrun a tornado.

Truth: Unless a car can maintain a speed of 40 to 65 miles per hour, there will not be much hope. Tornadoes quickly change directions so there is no sure escape route. Preceding a tornado, there can be hail big enough to break windshields, flash flooding, high winds, debris on the road and torrential rain so there is danger driving a car even before a tornado hits. If everybody decided to escape by car, the roads would be jammed. Stay home and take shelter in a safe location.

Tornado Myth: A car can provide safe shelter from a tornado.

Truth: Flying debris from any tornado can shatter car windows which can result in injury. Ground level winds can easily flip a car. Strong tornadoes have the capability of making cars airborne. It is better to seek safer shelter such as a structure or low ground.

Photo courtesy Dave Williams, Wichita Eagle

6

Preparation for a Tornado Tornadoes form and move quickly; there may not be much time for a warning. It is important to stay alert to weather conditions during severe storms. You need to have an emergency plan of evacuation or a safe place in the home to go to. Although there are no guaranteed safe places during a tornado, some locations are better than others. Before a tornado strikes, you should do the following:

Plan where you will go in the event of a tornado. Make plans for helping anyone with special needs (for example, in a wheelchair) to get to

the designated place. Ensure that the tornado safe place is properly prepared. Learn tornado danger signs. Beware of possible dangers:

o Flying objects o Falling trees o Broken windows o Collapsing buildings

Teach everyone in your family or unit about tornadoes, including the difference between a Tornado Watch and a Tornado Warning. Have a practice tornado drill. Make sure you have an emergency supply kit with the items listed below. It is a good idea to also have a NOAA Weather Radio with auto alert, for your country only.

It is good to assemble a tornado/disaster safety kit and keep it in the shelter area. The disaster safety kit should include supplies such as:

A first aid kit with essential medication (prescription and nonprescription) A portable battery operated radio with extra batteries A flashlight with extra batteries Emergency food: canned or other non-perishable items Hand operated can opener Bottled water Candles and matches Sturdy shoes and work gloves Written instructions on how to turn off your homes utilities Cash and credit cards Sanitary needs

NOAA Weather Radios

NOAA weather radios are the best way to receive warnings from the National Weather Service. By using a NOAA weather radio, you can receive continuous updates on all the weather conditions in your area. The range of these radios depends on where you live, but the average range is 40 miles. The radios are sold in many stores. The National Weather Service recommends buying a radio with a battery backup (in case the power goes off) and a tone-alert feature that automatically sounds when a weather watch or warning is issued.

7

Tornado Watches and Tornado Warnings It is important to know the difference between a tornado watch and a tornado warning.

A Tornado Watch simply means the conditions are favorable for a tornado to develop. Tornadoes are possible in your area. Remain alert for approaching storms.

A Tornado Warning is issued when spotters have sighted a funnel cloud, or a tornado has been located by weather radar. If a tornado warning is issued for your area and the sky becomes threatening, move to your pre-designated place of safety.

Educate yourself on your local emergency siren system. When a tornado warning is issued for Fort Leonard Wood, the emergency operations center will activate their Mass Notification System. Severe weather notifications consist of the following:

A steady tone for 60 seconds followed by a male voice stating: “May I have your attention? This is a severe weather warning. Take required actions and tune into local radio for the latest update.” This sequence is repeated three times.

Once the severe weather has passed, the All Clear announcement will be made:

7 cycles of the Westminster chime tone, followed by a male voice saying, “May I have your attention please? All clear. The emergency has ended.” This sequence is repeated three times.

What to do if a Tornado Approaches Each year many people are killed or seriously injured by tornadoes despite advance warning. Some do not hear the warning while others received the warning, but did not believe a tornado would actually affect them. Knowing what to do could save your life in the event a tornado threatens your area. After you have received the warning or observed threatening skies, you must make the decision to seek shelter before the storm arrives. It could be the most important decision you will ever make. If a Tornado Warning is issued or if threatening weather approaches:

Sound the alarm so others may be informed. If time permits, shut off electrical circuits and fuel supply lines. Immediately move to the pre-designated place. Get out of automobiles. Do not try to outrun a tornado in your car; instead, leave it immediately. Keep and eye on the sky. Look for darkening skies, flashes of light or increasing winds. Listen to the radio or TV station for additional information on the storm’s track.

8

The Safest Places to be in the Event of a Tornado

Where you go when a tornado is about to hit can make the difference between surviving and not surviving. You may have only minutes to get to a safe place. You must know where the designated place is and must go there quickly. Take the best shelter available that will afford the greatest protection to you from flying objects or collapse of structures. More persons are injured by flying glass and other flying objects than by collapsing building. In a Home or other Building: Frame, brick, and stone structures offer poor resistance to a tornado. If time does not permit evacuation of a wooden building, the best chance of survival is on the first floor, lying adjacent to the wall or corner nearest the tornado. In reinforced concrete buildings, stay inside on a lower floor near an interior wall and away from windows. Concrete walls between you and the approaching tornado offer good shelter from flying objects.

A long-span building, such as a shopping mall, theater, or gymnasium, is especially dangerous because the roof structure is usually supported solely by the outside walls. Most such buildings hit by tornados cannot withstand the enormous pressure. They simply collapse.

In theaters, warehouses, and auditoriums: Move quickly to a small interior room such as a rest room or closet. Otherwise, evacuate these buildings and seek shelter in nearby sturdy buildings, if time permits.

If you are in a long-span building during a tornado, stay away from windows. Get to the lowest level of the building - the basement if possible - and away from the windows.

In shopping centers: Go to a designated shelter area, or lie flat outside in a ditch or a low protected ground. Do not stay in your car, since it is an unsafe place during a tornado.

Extra care is required in offices, schools, hospitals, or any building where a large group of people is concentrated in a small area. The exterior walls of such buildings often have large windows. If you are in any of these buildings -

Move away from windows and glass doorways.

Go to the innermost part of the building on the lowest possible floor.

Do not use elevators because the power may fail, leaving you trapped.

Protect your head and make yourself as small a target as possible by crouching down.

In schools: All public schools have reliable ways to monitor tornado watches and warnings, and each school has a designated emergency plan that will lead pupils and faculty to designated safe areas. Teachers should lead students out of gyms, auditoriums and portable classrooms to interior rooms and hallways on ground level floors. Students should stay away from glass, both

9

in windows and doors. They should crouch down and seek shelter under a classroom desk, if possible. Otherwise, they should make themselves as small as possible, being sure to cover the head.

Best protection is found in storm cellars and basements. Go to the southwest corner of the basement. Get under sturdy furniture, if possible. If you have no basement, choose an inside wall, on the lowest floor, away from windows, and lie flat against it. This could be a center hallway, bathroom, or closet. Get under heavy furniture, if possible, to protect yourself from flying glass and debris.

For added protection, get under something sturdy such as a heavy table or workbench. If possible, cover your body with a blanket, sleeping bag, or mattress, and protect your head with anything available--even your hands. Avoid taking shelter where there are heavy objects, such as pianos or refrigerators, on the area of floor that is directly above you. They could fall though the floor if the tornado strikes your house.

Interior halls, bathrooms and closets are often good places. Get under heavy furniture, if possible, to protect yourself from flying glass and debris. If you have designated a bathroom as your safe area, get into the bathtub and cover yourself with a couch cushion. Stay away from windows. Draw blinds and shades closed it may prevent glass from shattering and falling inside your home. Use your hands and arms to protect your head and face. (See Photo 1 on next page) Avoid being near large objects that could easily tip over, such as bookcases, or large objects that could fall off walls or be blown around. Also avoid being around glass objects, which can become very dangerous, sharp projectiles in a tornado.

In mobile homes: Go to the nearest community shelter or other sturdy building if possible. Mobile homes are especially dangerous during high winds and may be overturned. All mobile homes should be tied down. But, even if tied down, they offer little protection from tornadoes. Most mobile home communities have a recreational building or laundry room which could offer safe haven. As a last resort, seek refuge in a ditch or culvert or other low lying area of ground.

Outdoors:

If in a car: Try to move away from the tornado's path at right angles. (Face the tornado and move to the right or left of it.) Remember, tornados generally move from the southwest to the northeast, therefore, if the tornado appears to be moving toward you, traveling south is the better choice. Never try to outrun a tornado in urban or congested areas in a car or truck. Instead, leave the vehicle immediately for safe shelter. If outside: If you have no time to escape, lie flat in the nearest ditch, ravine, culvert or under a bridge, but not where you could be trapped by flood waters. It is best if the ditch or ravine is at a

10

right angle to the path of the tornado. Cover your head with your hands. Be aware of the potential for flooding. Do not lie flat on the ground. Your body acts as a conductor for electricity which attracts lightning; instead squat low to the ground. (See Photo 2, below)

Do not get under an overpass or bridge. You are safer in a low, flat location. Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries. Avoid wooded areas, if possible, as tornadoes can uproot even the largest trees and convert them into deadly missiles.

Photo 1 Photo 2

Photo courtesy Bill Bunting Photo courtesy Todd Heitcamp

For more information on tornadoes, go to the following websites: National Weather Service: http://www.nws.noaa.gov/ Federal Emergency Management Agency: http://www.fema.gov/hazard/tornado/index.shtm