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Tornado!
Although tornadoes occur in many parts of the world, these
destructive forces of nature are found most frequently in the
United States east of the Rocky Mountains during the spring and
summer months. In an average year, 800 tornadoes are reported
nationwide, resulting in 80 deaths and over 1,500 injuries. A
tornado is defined as a violently rotating column of air
extending from a thunderstorm to the ground. The most violent
tornadoes are capable of tremendous destruction with wind speeds
of 250 mph or more. 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!

What causes tornadoes?
Thunderstorms develop in warm, moist air in advance of eastward-
moving cold fronts. These thunderstorms often produce large
hail, strong winds, and tornadoes. Tornadoes in the winter and
early spring are often associated with strong, frontal systems
that form in the Central States and move east. Occasionally,
large outbreaks of tornadoes occur with this type of weather
pattern. Several states may be affected by numerous severe
thunderstorms and tornadoes.

During the spring in the Central Plains, thunderstorms
frequently develop along a "dryline," which separates very warm,
moist air to the east from hot, dry air to the west. Tornado-
producing thunderstorms may form as the dryline moves east
during the afternoon hours.

Along the front range of the Rocky Mountains, in the Texas
panhandle, and in the southern High Plains, thunderstorms
frequently form as air near the ground flows "upslope" toward
higher terrain. If other favorable conditions exist, these
thunderstorms can produce tornadoes.

Tornadoes occasionally accompany tropical storms and hurricanes
that move over land. Tornadoes are most common to the right and
ahead of the path of the storm center as it comes onshore.


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Tornado Variations
Some tornadoes may form during the early stages of rapidly
developing thunderstorms. This type of tornado is most common
along the front range of the Rocky Mountains, the Plains, and
the Western States.
Tornadoes may appear nearly transparent until dust and debris
are picked up.
Occasionally, two or more tornadoes may occur at the same time.
Waterspout
Waterspouts are weak tornadoes that form over warm water.
Waterspouts are most common along the Gulf Coast and
southeastern states. In the western United States, they occur
with cold late fall or late winter storms, during a time when
you least expect tornado development.
Waterspouts occasionally move inland becoming tornadoes causing
damage and injuries.

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How Do Tornadoes Form?
Before thunderstorms develop, a change in wind direction and an
increase in wind speed with increasing height creates an
invisible, horizontal spinning effect in the lower atmosphere.

Rising air within the thunderstorm updraft tilts the rotating
air from horizontal to vertical.

An area of rotation, 2-6 miles wide, now extends through much of
the storm. Most strong and violent tornadoes form within this
area of strong rotation.

A lower cloud base in the center of the photograph identifies an
area of rotation known as a rotating wall cloud. This area is
often nearly rain-free. Note rain in the background.

Moments later a strong tornado develops in this area. Softball-
size hail and damaging "straight-line" winds also occurred with
this storm.


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Tornadoes Take Many
Shapes and Sizes
Weak Tornadoes
69% of all tornadoes
Less than 5% of tornado deaths
Lifetime 1-10+ minutes
Winds less than 110 mph
Strong Tornadoes
29% of all tornadoes
Nearly 30% of all tornado deaths
May last 20 minutes or longer
Winds 110-205 mph
Violent Tornadoes
Only 2% of all tornadoes
70% of all tornado deaths
Lifetime can exceed 1 hour
Winds greater than 205 mph
Tornado Myths:
MYTH: Areas near rivers, lakes, and mountains are safe from
tornadoes.
FACT: No place is safe from tornadoes. In the late 1980's, a
tornado swept through Yellowstone National Park leaving a path
of destruction up and down a 10,000 ft. mountain.


MYTH: The low pressure with a tornado causes buildings
to "explode" as the tornado passes overhead.
FACT: Violent winds and debris slamming into buildings cause
most structural damage.

MYTH:Windows should be opened before a tornado approaches to
equalize pressure and minimize damage.
FACT: Opening windows allows damaging winds to enter the
structure. Leave the windows alone; instead, immediately go to a
safe place.


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Tornadoes Occur Anywhere
Carolinas Outbreak:
March 28, 1984, afternoon-evening
22 tornadoes
57 deaths
1,248 injuries
damage $200 million
37% of fatalities in mobile homes

Pennsylvania-Ohio Outbreak:
May 31, 1985, late afternoon-evening
41 tornadoes, including 27 in PA and OH
75 deaths in U.S.
1,025 injuries
damage $450 million

Plains Outbreak:
April 26-27, 1991, afternoon of 26th through early morning 27th
54 tornadoes
21 deaths
308 injuries
damage $277+ million
15 deaths in/near mobile homes, 2 deaths in vehicles

Weather Radar Watches the Sky
Meteorologists rely on weather radar to provide information on
developing storms. The National Weather Service is strategically
locating Doppler radars across the country which can detect air
movement toward or away from the radar. Early detection of
increasing rotation aloft within a thunderstorm can allow life-
saving warnings to be issued before the tornado forms.


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Frequency of Tornadoes
Tornadoes can occur at any time of the year.
In the southern states, peak tornado occurrence is in March
through May, while peak months in the northern states are during
the summer.
Note, in some states, a secondary tornado maximum occurs in the
fall.
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.
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.
The total number of tornadoes is probably higher than indicated
in the western states. Sparce population reduces the number
reported.

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STAY INFORMED ABOUT THE STORM
by listening to NOAA Weather Radio, commercial radio, and
television for the latest tornado WATCHES and WARNINGS.
When conditions are favorable for severe weather to develop, a
severe thunderstorm or tornado WATCH is issued.

Weather Service personnel use information from weather radar,
spotters, and other sources to issue severe thunderstorm and
tornado WARNINGS for areas where severe weather is imminent.

Severe thunderstorm warnings are passed to local radio and
television stations and are broadcast over local NOAA Weather
Radio stations serving the warned areas. These warnings are also
relayed to local emergency management and public safety
officials who can activate local warning systems to alert
communities.

NOAA WEATHER RADIO IS THE BEST MEANS TO RECEIVE WARNINGS FROM
THE NATIONAL WEATHER SERVICE
The National Weather Service continuously broadcasts updated
weather warnings and forecasts that can be received by NOAA
Weather Radios sold in many stores. The average range is 40
miles, depending on topography. Your National Weather Service
recommends purchasing a radio that has both a battery backup and
a tone-alert feature which automatically alerts you when a watch
or warning is issued.

What To Listen For...

TORNADO WATCH: Tornadoes are possible in your area. Remain alert
for approaching storms.
TORNADO WARNING: A tornado has been sighted or indicated 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.
SEVERE THUNDERSTORM WATCH: Severe thunderstorms are possible in
your area.
SEVERE THUNDERSTORM WARNING: Severe thunderstorms are occurring.

Remember, tornadoes occasionally develop in areas in which a
severe thunderstorm watch or warning is in effect. Remain alert
to signs of an approaching tornado and seek shelter if
threatening conditions exist.


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Environmental Clues
Look out for:
Dark, often greenish sky
Wall cloud
Large hail
Loud roar; similar to a freight train
Caution:
Some tornadoes appear as a visible funnel extending only
partially to the ground. Look for signs of debris below the
visible funnel.

Some tornadoes are clearly visible while others are obscured by
rain or nearby low-hanging clouds.

Other Thunderstorm Hazards
These dangers often accompany thunderstorms:
Flash Floods: Number ONE weather killer - 146 deaths annually
Lightning: Kills 75-100 people each year
Damaging Straight-line Winds: Can reach 140 mph
Large Hail: Can reach the size of a grapefruit - causes several
hundred million dollars in damage annually to property and crops
Contact your local National Weather Service office, American Red
Cross chapter, or Federal Emergency Management Agency office for
a copy of the "Thunderstorms and Lightning...The Underrated
Killers" brochure (NOAA PA 92053) and the "Flash Floods and
Floods...The Awesome Power" brochure (NOAA PA 92050).


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Tornado Safety
What YOU Can Do
Before the Storm:
Develop a plan for you and your family for home, work, , school
and when outdoors.
Have frequent drills.
Know the county/parish in which you live, and keep a highway map
nearby to follow storm movement from weather bulletins.
Have a NOAA Weather Radio with a warning alarm tone and battery
back-up to receive warnings.
Listen to radio and television for information.
If planning a trip outdoors, listen to the latest forecasts and
take necessary action if threatening weather is possible.
If a Warning is issued or if threatening weather approaches:
In a home or building, move to a pre-designated shelter, such as
a basement.
If an underground shelter is not available, move to an interior
room or hallway on the lowest floor and get under a sturdy piece
of furniture.
Stay away from windows.
Get out of automobiles.
Do not try to outrun a tornado in your car; instead, leave it
immediately.
Mobile homes, even if tied down, offer little protection from
tornadoes and should be abandoned.
Occasionally, tornadoes develop so rapidly that advance warning
is not possible. Remain alert for signs of an approaching
tornado. Flying debris from tornadoes causes most deaths and
injuries.
It's Up To YOU!
Each year, many people are killed or seriously injured by
tornadoes despite advance warning. Some did not hear the warning
while others received the warning but did not believe a tornado
would actually affect them. The preparedness information in this
brochure, combined with timely severe weather watches and
warnings, 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.

Who's Most At Risk?
People in automobiles
The elderly, very young, and the physically or mentally impaired
People in mobile homes
People who may not understand the warning due to a language
barrier

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Tornado Safety in Schools
EVERY School Should Have A Plan!
Develop a severe weather action plan and have frequent drills,
Each school should be inspected and tornado shelter areas
designated by a registered engineer or architect. Basements
offer the best protection. Schools without basements should use
interior rooms and hallways on the lowest floor and away from
windows.
Those responsible for activating the plan should monitor weather
information from NOAA Weather Radio and local radio/television.
If the school's alarm system relies on electricity, have a
compressed air horn or megaphone to activate the alarm in case
of power failure.
Make special provisions for disabled students and those in
portable classrooms.
Make sure someone knows how to turn off electricity and gas in
the event the school is damaged.
Keep children at school beyond regular hours if threatening
weather is expected. Children are safer at school than in a bus
or car. Students should not be sent home early if severe weather
is approaching.
Lunches or assemblies in large rooms should be delayed if severe
weather is anticipated. Gymnasiums, cafeterias, and auditoriums
offer no protection from tornado-strength winds.
Move students quickly into interior rooms or hallways on the
lowest floor. Have them assume the tornado protection position
(shown at right).
Hospitals, nursing homes, and other institutions should develop
a similar plan
Your National Weather Service, Federal Emergency Management
Agency, and American Red Cross educate community officials and
the public concerning the dangers posed by tornadoes. YOU can
prepare for the possibility of a tornado by learning the safest
places to seek shelter when at home, work, school, or outdoors.
You should also understand basic weather terms and danger signs
related to tornadoes. Your chances of staying safe during a
tornado are greater if you have a plan for you and your family,
and practice the plan frequently.


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FAMILY DISASTER PLAN
Families should be prepared for all hazards that affect their
area. NOAA's National Weather Service, the Federal Emergency
Management Agency, and the American Red Cross urge each family
to develop a family disaster plan.

Where will your family be when disaster strikes? They could be
anywhere - at work, at school, or in the car. How will you find
each other? Will you know if your children are safe? Disasters
may force you to evacuate your neighborhood or confine you to
your home. What would you do if basic services - water, gas,
electricity or telephones - were cut off?

Follow these basic steps to develop a family disaster plan...



I. Gather information about hazards. Contact your local National
Weather Service office, emergency management or civil defense
office, and American Red Cross chapter. Find out what type of
disasters could occur and how you should respond. Learn your
community's warning signals and evacuation plans.

II. Meet with your family to create a plan. Discuss the
information you have gathered. Pick two places to meet: a spot
outside your home for an emergency, such as fire, and a place
away from your neighborhood in case you can't return home.
Choose an out-of-state friend as your "family check-in contact"
for everyone to call if the family gets separated. Discuss what
you would do if advised to evacuate.

III. Implement your plan.
(1) Post emergency telephone numbers by phones;
(2) Install safety features in your house, such as smoke
detectors and fire extinguishers;
(3) Inspect your home for potential hazards (such as items that
can move, fall, break, or catch fire) and correct them;
(4) Have your family learn basic safety measures, such as CPR
and first aid; how to use a fire extinguisher; and how and when
to turn off water, gas, and electricity in your home;
(5) Teach children how and when to call 911 or your local
Emergency Medical Services number;
(6) Keep enough supplies in your home to meet your needs for at
least three days. Assemble a disaster supplies kit with items
you may need in case of an evacuation. Store these supplies in
sturdy, easy-to-carry containers, such as backpacks or duffle
bags. Keep important family documents in a waterproof container.
Keep a smaller disaster supplies kit in the trunk of your car.
A DISASTER SUPPLIES KIT SHOULD INCLUDE:
A 3-day supply of water (one gallon per person per day) and food
that won't spoil
one change of clothing and footwear per person
one blanket or sleeping bag per person
a first-aid kit, including prescription medicines
emergency tools, including a battery-powered NOAA Weather Radio
and a portable radio, flashlight, and plenty of extra batteries
an extra set of car keys and a credit card or cash
special items for infant, elderly, or disabled family members.


IV. Practice and maintain your plan. Ask questions to make sure
your family remembers meeting places, phone numbers, and safety
rules. Conduct drills. Test your smoke detectors monthly and
change the batteries at least once a year. Test and recharge
your fire extinguisher(s) according to manufacturer's
instructions. Replace stored water and food every six months.



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