Tornado
Why Talk About Tornadoes?
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Tornadoes have been reported in every state, and
though they generally
occur during spring and summer, they can happen any time of the year.
While
tornadoes can occur at any time of the day or night, they are
most likely
to occur between 3:00 and 9:00 p.m. There are no areas immune
to tornadoes;
they have been reported in mountains and valleys, over deserts and
swamps,
from the Gulf Coast into Canada, in Hawaii and even Alaska. Regardless
of the location or time of year, if conditions are right, a tornado can
happen. Over 1,000 tornadoes are reported annually nationwide, and as
our
tornado detection systems improve, more are being reported each year.
However,
sometimes tornadoes will develop in areas in which no tornado watch or
warning is in effect, so stay alert for changing weather conditions.
What Are Tornadoes, and What Causes Them?
A tornado is a violently rotating column of air extending from
a thunderstorm
to the ground. The most violent tornadoes have rotating winds
of 250
miles per hour or more. They are capable of causing extreme
destruction,
including uprooting trees and well-made structures, and turning
normally
harmless objects into deadly missiles. Most tornadoes are just a few
dozen
yards wide and only briefly touch down, but highly destructive violent
tornadoes may carve out paths over a mile wide and more than 50 miles
long.
Although violent tornadoes comprise only 2 percent of all tornadoes,
they
are responsible for nearly 70 percent of tornado-related fatalities.
Tornadoes develop from severe thunderstorms in warm,
moist, unstable
air along and ahead of cold fronts. Such thunderstorms also
may generate
large hail and damaging winds. When intense springtime storm systems
produce
large, persistent areas that support tornado development, major
outbreaks
can occur. During the late spring, tornadic thunderstorms can
develop
in the southern High Plains along a "dry line," the interface
between
warm, moist air to the east and hot, dry air to the west. From the
front
range of the Rocky Mountains southward into the Texas Panhandle, slope
flow of unstable air can cause tornadic thunderstorms to develop. While
generally smaller and not as frequent, tornadoes occurring west of the
Rocky Mountains of the United States also cause damage and threaten
lives
annually.
Landfalling tropical storms and hurricanes also
generate tornadoes.
Such tornadoes are most common to the right and ahead of the storm path
or the storm center as it comes ashore. In 1967, Hurricane Beulah
produced
148 tornadoes as it made landfall in south Texas.
While tornadoes can be highly destructive and are
potentially deadly,
timely precautions can save lives and reduce property damage.
During
active weather, stay alert of the forecast by listening to radio or
television
or by using a NOAA Weather Radio. Contact your local National Weather
Service
(NWS) office, emergency management agency, or
American Red Cross chapter for more information about your
risk from
tornadoes.
Awareness Information
A National
Weather Service WATCH
is
a message indicating that conditions favor the occurrence of a certain
type of hazardous weather. For example, a severe thunderstorm watch
means
that a severe thunderstorm is expected in the next six hours or so
within
an area approximately 120 to 150 miles wide and 300 to 400 miles long
(36,000
to 60,000 square miles). The NWS Storm Prediction Center issues such
watches.
Local NWS forecast offices issue other watches (flash flood, winter
weather,
etc.) 12 to 36 hours in advance of a possible hazardous-weather or
flooding
event. Each local forecast office usually covers a state or a portion
of
a state.
An NWS WARNING indicates that a hazardous
event is occurring
or is imminent in about 30 minutes to an hour. Local NWS forecast
offices
issue warnings on a county-by-county basis.
Tornadoes may appear nearly
transparent until dust and
debris are picked
up. Stay alert for high winds even if you do not "see" a
tornado.
Tornadoes often occur when it is not raining.
In
fact, in the Great
Plains and other semiarid regions, that scenario is the rule rather
than
the exception. Tornadoes are associated with a powerful updraft, so
rain
does not fall in or next to a tornado. Very large hail, however, does
fall
in the immediate area of the tornado. In humid environments, rain often
tends to wrap around the tornado, being pulled from the main
precipitation
area around the outside of the rotating updraft. The rain could make it
difficult to see the tornado.
Waterspouts are weak tornadoes that form over
warm water
and are most
common along the Gulf Coast and southeastern states. In the
western
United States, waterspouts occur with cold late fall or late winter
storms,
during a time when you least expect tornado development. Waterspouts,
which
are tornadoes over a body of water, occasionally move inland becoming
tornadoes
and causing damage and injuries.
Damage happens when wind gets inside a home
through a
broken window,
door, or damaged roof. Keep windows closed. Houses do not
explode due
to air pressure differences. Stay away from windows during severe
storms.
Flying debris could shatter the glass and cause injury.
It used to be advised to go to the southwest
corner for
safety; however,
the southwest corner of a house is no safer than any other corner.
Historical information has shown that any corner on the lowest level
away
from windows is as safe as any other corner. If tornado winds enter the
room, debris has a tendency to collect in corners. When selecting a
tornado
"safe place," look for a place on the lowest level and away from
windows,
preferably in a small room (closet or bathroom) in the center of the
house.
Closer walls will help provide more support to the roof, and each wall
between you and the outside will provide further protection.
Folklore passed down through the generations
used to
advise opening
windows in case of a tornado because air pressure differences would
cause
a house to explode. This information is not true. Air
pressure differences
in a tornado are not strong enough to cause a house to explode; houses
are damaged by the violent winds associated with a tornado and from the
debris blown at high velocities by tornado winds.
Folklore also used to advise that if you are
driving and a
tornado is
suspected or sighted, you should turn and drive at right angles to the
storm. This advice is not recommended because tornadoes do
not necessarily
travel in straight lines; you cannot always tell the direction the
storm
is coming from; the road you turn onto may curve and head into the
storm,
rather than away from it; and there may be more than one tornado
associated
with a strong storm system, but you may not see it because visibility
is
diminished by heavy rain and wind-blown debris. The safest
thing to
do is go to a nearby sturdy building and go inside to an area on the
lowest
level, without windows. If a sturdy building is not
available, then
get out of the vehicle and lay down in a low spot on the ground not
subject
to flooding, protecting the head and neck
Plan for a Tornado
Develop a Family Disaster Plan. Please see the "Family
Disaster Plan" section
for general family
planning information. Tornado-specific planning should include the
following:
- Learn about your tornado risk. While
severe
tornadoes are more frequent
in the Plains States, tornadoes have happened in every state. Contact
your
local emergency management office, local National Weather Service
office,
or American Red Cross chapter for more information on tornadoes.
- Pick a safe place in your home where family
members could
gather during
a tornado. The safest place to be is underground, or as low
to the
ground as possible, and away from all windows. If you have a basement,
make it your safe place. If you do not have a basement, consider an
interior
hallway or room on the lowest floor. Putting as many walls as you can
between
you and the outside will provide additional protection. Less than 2
percent
of all tornadoes are powerful enough to completely destroy a sturdy
building.
Make sure there are no windows or glass doors in your safe place and
keep
this place uncluttered.
- Consider having your tornado safe place
reinforced.
Additional reinforcement
will add more protection from the damaging effects of tornado winds.
Get
more information from FEMA
about building
a tornado safe room. (See "Resources" section.)
- If you are in a high-rise building, pick a place
in a
hallway in the
center of the building. You may not have enough time to go to
the lowest
floor. Center hallways are often structurally the most reinforced part
of a building.
- If you live in a mobile home, choose a safe
place in a
nearby sturdy
building. A sturdy building provides greater protection. If
your mobile
home park has a designated shelter, make it your safe place. Mobile
homes
are much more vulnerable to strong winds than site-built structures.
Prior
to 1994, most manufactured homes were not designed to withstand even
moderate
winds.
- Discuss how you would be warned of an
approaching tornado.
Different
communities have different ways of providing warnings. Many communities
have sirens intended for outdoor warning purposes. Use a NOAA Weather
Radio
with a tone-alert feature to keep you aware of watches and warnings
while
you are indoors. Learn about your community's warning system. Make sure
all family members know the name of the county or parish where you live
or are traveling, because tornado watches and warnings are issued for a
county or parish by name.
- Learn about your community's warning system.
Different communities
have different ways of providing warnings. Many communities have sirens
intended for outdoor warning purposes. Use a NOAA Weather Radio with a
tone-alert feature to keep you aware of watches and warnings while you
are indoors.
- Conduct periodic tornado drills, so everyone
remembers
what to do when
a tornado is approaching. Practice having everyone in the
family go
to your designated area in response to a tornado threat. Practicing
your
plan makes the appropriate response more of a reaction, requiring less
thinking time during an actual emergency situation.
- Check with your work and your children's schools
and day
care centers
to learn tornado emergency plans. Every building has
different safe
places. It is important to know where they are and how to get there in
an emergency.
- Discuss tornadoes with your family.
Everyone
should know what to
do in case all family members are not together. Discussing disaster
ahead
of time helps reduce fear and lets everyone know how to respond during
a tornado.
What to Tell Children
- Find safe places in your home and classroom.
Make sure these places
are away from windows and tall furniture that could tip over. In your
safe
place, get under something sturdy, or use a large, hard-cover book to
help
protect your head and neck from flying or falling objects. Locate safe
places outside in case you are not able to go inside. Frequently,
children
in schools are told to move to the inner hallways away from windows.
Children
need to know that a tornado safe place is not the same as a fire
meeting
place.
- Wherever you are, if you hear or see a tornado
coming,
take cover right
away. Tornadoes can move quickly, blowing objects at very
high speeds,
even if they are a distance away. Protect yourself from flying debris
by
taking cover immediately.
- If you're in a house or apartment building and a
tornado
threatens,
go to the lowest level - a basement or storm cellar if possible. Once
on
the lowest level, go to the middle of the building away from windows,
into
a bathroom or closet if possible. The safest place to be is
under the
ground, or as low to the ground as possible, and away from all windows.
If you have a basement, make it your safe place. If you do not have a
basement,
consider an interior hallway or room on the lowest floor. Putting as
many
walls as you can between you and the outside will provide additional
protection.
Make sure there are no windows or glass doors in your safe place and
keep
this place uncluttered.
- Get under something sturdy, such as a heavy
table, hold on
and stay
there until the danger has passed. Being under something
heavy will
help protect you from falling objects. If tornado wind enters the room
and the object moves, holding on with one hand will help you move with
it, keeping you protected.
- Use your other arm and hand to protect your head
and neck
from falling
or flying objects. Your head and neck are more easily injured
than
other parts of your body. Protect them as much as you can.
- If you're outside in a car or in a mobile home,
go
immediately to the
basement of a nearby sturdy building. Sturdy buildings are
the safest
place to be. Tornado winds can blow large objects, including cars,
hundreds
of feet away. Tornadoes can change direction quickly and can lift up a
car or truck and toss it through the air. Never try to out-drive a
tornado.
Mobile homes are particularly vulnerable. A mobile home can overturn
very
easily even if precautions have been taken to tie down the unit.
- If there is no building nearby, lie flat in a
low spot.
Use your arms
and hands to protect your head. Tornadoes cause a lot of
debris to
be blown at very high speeds, and you can be hurt by this debris if it
hits you. Dangerous flying debris can be blown under highway overpasses
and bridges, or weaker overpasses and bridges could be destroyed. You
will
be safer lying flat in a low-lying area where wind and debris will blow
above you. Tornadoes come from severe thunder- storms, which can
produce
a lot of rain. If you see quickly rising water or flood water coming
towards
you, move to another spot.
How to Protect Your Property
- Make a list of items to bring inside in the
event of a
storm. Having
a list will help you remember things that may be broken or blown away
in
strong winds.
- Keep trees and shrubbery trimmed. Make
trees
more wind resistant
by removing diseased or damaged limbs, then strategically remove
branches
so that wind can blow through. Strong winds frequently break weak limbs
and hurl them at great speed, causing damage or injury when they hit.
Debris
collection services may not be operating just before a storm, so it is
best to do this well in advance of approaching storms.
- Remove any debris or loose items in your yard.
Branches and firewood
may become missiles in strong winds.
- Consider installing permanent shutters to cover
windows.
Shutters
can be closed quickly and provide the safest protection for windows.
- Strengthen garage doors. Garage doors
are often
damaged or destroyed
by flying debris, allowing strong winds to enter. As winds apply
pressure
to the walls, the roof can be lifted off, and the rest of the house can
easily follow.
Assemble a Disaster
Supplies Kit
Please see the section "Disaster
Supplies Kit"
for
general supplies kit information. Tornado-specific supplies should
include
the following:
- A highway map to follow storm movement from
weather
bulletins.
- Disaster Suplies Kit basics.
Media and Community Education Ideas
- 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 chapter,
and
the nearest hospitals.
- Periodically inform your community of local
public warning
systems.
- Sponsor a "Helping Your Neighbors" 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.
- 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.
- Interview local officials about what people living
in mobile
home parks
should do if a tornado warning is issued.
What to Do Before a Tornado
- Use a NOAA Weather Radio with a tone-alert
feature to keep
you informed
of watches and warnings issued in your area. The tone- alert
feature
will automatically alert you when a watch or warning is issued.
- If planning a trip or extended period of time
outdoors,
listen to the
latest forecasts and take necessary action if threatening weather is
possible.
Knowing what weather could happen helps you be prepared to respond if
necessary.
Having a raincoat, umbrella, and disaster supplies kit available will
make
it easier to deal with severe weather if it occurs.
- Watch for tornado danger signs.
Tornadoes may
happen so quickly
warnings can't be issued long in advance. Pay attention to weather
clues
around you that may warn of imminent danger.
- Dark, often greenish sky. Sometimes
one or
more of the clouds turns
greenish (a phenomenon caused by hail) indicating a tornado may develop.
- Wall cloud, an isolated lowering of
the base
of a thunderstorm.
The wall cloud is particularly suspect if it is rotating.
- Large hail. Tornadoes are spawned
from
powerful thunderstorms and
the most powerful thunderstorms produce large hail. Tornadoes
frequently
emerge from near the hail-producing portion of the storm.
- Cloud of debris. An approaching
cloud of
debris can mark the location
of a tornado even if a funnel is not visible.
- Funnel cloud. A visible rotating
extension of
the cloud base is
a sign that a tornado may develop.
- Roaring noise. The high winds of a
tornado
can cause a roar that
is often compared with the sound of a freight train.
- Tornadoes may occur near the trailing edge of
a
thunderstorm and be
quite visible. It is not uncommon to see clear, sunlit skies
behind
a tornado. They may also be embedded in rain and not visible at all.
If you live in a single-family home in a
tornado-prone area, find
out how to reinforce an interior room on the lowest level of your home
(such as the basement, storm cellar, bathroom or closet) to use as a
shelter.
Plans for reinforcing an interior room to provide better tornado
protection
in your home are available from your local emergency management office
or from FEMA's website at
www.fema.gov.
What to Do During a Tornado WATCH
- Listen to a NOAA
Weather Radio
or local radio or television stations for updated information.
Tornadoes
can change direction, intensity, and speed very quickly.
- Be alert to changing weather conditions.
Tornadoes accompany severe
thunderstorms, and weather conditions can change rapidly. Large hail,
blowing
debris, or the sound of an approaching tornado may alert you. Many
people
say approaching tornadoes sound like a freight train.
What to Do During a Tornado WARNING
- Listen to a battery-powered NOAA Weather Radio,
regular
radio, or television
for updated information. If the electricity should go out,
you will
still be able to receive emergency information.
- If you are inside, go to your safe place to
protect
yourself from glass
and other flying objects. Tornadoes can change direction,
intensity,
and speed very quickly. The tornado may be approaching your area.
- Get under a piece of sturdy furniture, such as a
workbench
or heavy
table, and hold on to it. Sturdy furniture will help protect
you from
falling debris. If tornado wind enters the room and the object moves,
holding
on with one hand will help you move with it, keeping you protected.
- Use your other arm and hand to protect your head
and neck
from falling
or flying objects. Your head and neck are more easily injured
than
other parts of your body. Protect them as much as you can.
- Stay away from windows. Opening
windows allows
damaging winds to
enter the structure. Leave the windows alone; instead, immediately go
to
a safe place. It is a myth that tornadoes cause houses to explode due
to
changes in air pressure. Flying debris can shatter glass. Violent winds
and debris slamming into buildings cause most structural damage.
- If you're outside in a car or in a mobile home,
go
immediately to the
basement of a nearby sturdy building. Sturdy buildings are
the safest
place to be. Tornado winds can blow large objects, including cars and
mobile
homes, hundreds of feet away. Tornadoes can change direction quickly
and
can lift up a car or truck and toss it through the air; never try to
out-drive
a tornado. Mobile homes are particularly vulnerable. A mobile home can
overturn very easily even if precautions have been taken to tie down
the
unit.
- If there is no building nearby, lie flat in a
low spot.
Use your
arms and hands to protect your head. Tornadoes cause a lot of debris to
be blown at very high speeds, and you can be hurt by this debris if it
hits you. Dangerous flying debris can be blown under highway overpasses
and bridges, or weaker overpasses and bridges could be destroyed. You
will
be safer lying flat in a low-lying area where wind and debris will blow
above you. Tornadoes come from severe thunderstorms, which can produce
a lot of rain. If you see quickly rising water or flood water coming
towards
you, move to another spot.
- Avoid places with wide-span roofs, such as
auditoriums,
cafeterias,
large hallways, or shopping malls. Wide-span roofs are
frequently damaged
or destroyed in tornado winds, providing less protection and more risk
of injury, than roofs over smaller rooms.
What to Do After a Tornado
- Continue listening to local radio or television
stations
or a NOAA Weather
Radio for updated information and instructions. Access may be
limited
to some parts of the community, or roads may be blocked.
- Help a neighbor who may require special
assistance -
infants, elderly
people and people with disabilities. Elderly people and
people with
disabilities may require additional assistance. People who care for
them
or who have large families may need additional assistance in emergency
situations.
- Help injured or trapped persons. Give
first aid
where appropriate.
Do not move seriously injured persons unless they are in immediate
danger
of further injury. Call for help.
- Watch out for fallen power lines or broken gas
lines and
report them
to the utility company immediately. Reporting potential
hazards will
get the utilities turned off as quickly as possible, preventing further
hazard and injury.
- Avoid disaster areas. Your presence
might hamper
rescue and other
emergency operations, and put you at further risk from the residual
effects
of tornadoes.
- Stay out of damaged buildings.
Tornadoes can
cause great damage,
creating further hazards. If you are away from home, return only when
authorities
say it is safe.
- When entering damaged buildings, use extreme
caution.
Moving through
debris presents further hazards. Carefully watch every step you take.
- Wear sturdy shoes. The most common
injury
following a disaster is
cut feet.
- Use battery-powered lanterns or flashlights
when
examining buildings.
Battery-powered lighting is the safest and easiest, preventing fire
hazard
for the user, occupants, and building.
- Examine walls, floors, doors, staircases, and
windows to
make sure that
the building is not in danger of collapsing.
- Look for fire hazards. There may be
broken or
leaking gas lines,
or damage to electrical systems. Clean up spilled medicines, bleaches,
gasoline, or other flammable liquids immediately. Fire is the
most frequent
hazard following other disasters.
- 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
using
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 burning 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.
Electrical equipment should be checked and dried before being returned
to service.
- Watch for loose plaster, drywall, and ceilings
that
could fall.
- Take pictures of the damage, both of the
building and
its contents,
for insurance claims.
Use the telephone only
for emergency calls. Telephone
lines are frequently overwhelmed in disaster situations. They need to
be
clear for emergency calls to get through.
Produced by the National
Disaster
Education Coalition: American
Red Cross, FEMA,
IAEM, IBHS, NFPA, NWS, USDA/CSREES,
and USGS. HTML
formating By the
Disaster Center
From: Talking About Disaster: Guide for Standard
Messages. Produced
by the National Disaster Education Coalition, Washington, D.C., 1999.
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