Tornadoes

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Tornadoes
Defined as a violently rotating column of air
extending from a thunderstorm to the ground.

• Occur in many parts of the world
• Found most frequently in the United States east
  of the Rocky Mountains
• Most frequent during the spring and summer
  months.
• An average of 800 tornadoes are reported
  nationwide each year
• 80 deaths and over 1,500 injuries average per
  year.
• 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.

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Tornado Formation cont.d...
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Tornado Formation

• Change in wind direction along with an increase
  of speed causes horizontal spinning effect.

• Rotating air tilts becoming vertical, forming
  funnel shape.

• Funnel extends to the ground becoming the
  Tornado.

• Wall cloud-slow rotating cloud, parent to the
  Tornado.

• If you see a rotating cloud in a
  thunderstorm-take no chances

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Tornado Formation
how tornadoes form
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When and Where they occur

• Mainly in the US but can occur anywhere

• Southern states- March-May

• Northern states- Summer months.

historical data Black Hawk County
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Watches versus Warnings
Many people confuse their meanings
Watch- tornadoes are possible in your area 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 coworkers where the safest places
within your office are located, and listen to the
radio or television for further developments.
Warning- tornadoes have been sighted by weather
radar
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• Look out for
• Dark, often greenish sky
• Wall cloud
• Large hail
• Loud roar similar to a freight train

Tornado Clues
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 can occur with this storm.
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• Some tornadoes may form during the early stages
  of rapidly developing thunderstorms.
• Occasionally, two or more tornadoes may occur at
  the same time.

Tornado Variations

• Tornadoes may appear nearly transparent until
  dust and debris are picked up.

• Waterspouts are weak tornadoes that form over
  warm water.

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Different types of Tornado

• The Wedge Tornado

• Straight on sides- not funnel shaped.

• Not stronger than a funnel shape but cover
  larger areas causing more damage.

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Different types of Tornado

• Another wedge with a different appearance

• Often blamed for striking without warning.

• Appear as a boiling well of fog as they are
  positioned close to the rain wall.

• The rain stops and the tornado appears

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Different types of Tornado

• Classic funnel but white.

• Tornado seen here is front lit by the sunlight
  so appears white

• Most Tornadoes are photographed from the west so
  appear black or grey

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Different types of Tornado

• Discontinuous funnel in the rain

• This funnel made a sudden appearance from out of
  the rain.

• An example of what might lurk in a tornadic storm

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Classification of Tornadoes

• Enhanced Fujita Scale

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__ ________ ___

• Tornadoes hide in many ways -- under cover of
  darkness, heavy rain, landscape.
• They usually 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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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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• In a home or building, move to a pre-designated
  shelter, such as a basement.
• Stay away from windows
• 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.

Tornado Safety
Interior bathroom was all that was left standing
of this house

• Mobile homes, even if tied down, offer little
  protection from tornadoes and should be abandoned.

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Tornado Safety at Work

• Go to an inside hallway at the lowest level
• Stay inside
• Avoid places with wide-span roofs areas
• Move away from exterior walls and windows
• Use arms to protect head and neck.

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Tornado Safety

• Get out of automobiles.
• Do not try to outrun a tornado in your car
  instead, leave it immediately.

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Vehicle Procedures During a Tornado

• Never try to out drive 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.

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Procedures for 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.

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Before A Tornado Happens
Take seriously the tornado drills we participate
here at HJH. Know what the siren means!
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Destruction caused by Tornadoes
Its troublesome when youve got
no home to
come home to.
Schools out!
Just as well there was no-one in
this car!
This church was never the same again
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Summary

• Tornadoes are a serious problem causing
  widespread devastation.

• Quick thinking could save lives

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Stay Safe!