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MORE TORNADO
FACTS |
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A
tornado is a violently rotating column of air that extends from the base
of a thunderstorm to the ground. Wind speeds within this swirling
column can range from 100 to 300 miles per hour.
Tornadoes
come in a variety of shapes and sizes. Some are visible from the
thunderstorm all the way to the ground, while in other cases only the
debris near the ground is visible. The tornado funnel can look
like the trunk of an elephant or a narrow rope. Occasionally a
tornado will be embedded in heavy rain showers and barely visible,
however, this is a fairly rare occurrence in Iowa. The width of a
tornado can vary from just a few feet to almost a mile, and the path
length can range from only a few yards to over 100 miles.
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Tornadoes
can appear in a number of colors: black, white, gray , blue,
green, and at times red or orange. The color of a tornado is
determined by numerous factors including the time of day, the presence
or absence of hail and the type of debris the tornado is picking
up. A tornado can also change color during its lifetime. |
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Although
tornadoes can occur anytime, the most favorable time of the year are the
spring and summer months, April through September. The peak months
for tornado occurrence are May and June, with the afternoon and evening
hours . . . between 2:00 p.m. and 12:00 midnight . . . being the most
favorable. |
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Most
tornadoes in Iowa . . . about 70 percent . . . move from the southwest
to the northeast. The other 30 percent move from the northwest to
the southeast . . these are most common during the summer months. |
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Each
year an average of 33 tornadoes skip across Iowa. Fortunately a
majority of these storms . . . about 70 percent . . . fall into
the weak category, with winds averaging perhaps 125 miles an hour.
These storms are difficult to warn for because they are not easily
detected by radar or trained spotters; they are also much less
likely to kill because of their narrow, short paths.
"Medium" and "Maxi", or violent tornadoes pose the
greatest danger to life and property. These storms are often
preceded by warnings, because these bigger and longer-lived tornadoes
are more easily detected by both radar and observers . |
HOW TO BE
PREPARED |
- 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.
- Discuss
with family members the difference between a "tornado
watch" and a "tornado warning".
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- 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".
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- Tornado
Watches and Warnings
- A
tornado watch is issued by the National Weather Service when
weather conditions are such that tornadoes are likely to
develop. This is the 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 radar. The danger is very serious and
everyone should go to a safe place, turn on a battery
operated radio and wait for further instructions.
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- 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 a ditch or low-lying
area a safe distance away from the unit.
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Tornado
Danger Signs |
| Learn
these tornado danger signs: |
| 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. |
| Calm
before the storm: Before a tornado hits, the wind may die
down and the air may become very still. |
| 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. A tornado is evident when one or
more of the clouds turns greenish (a phenomenon caused by hail) and a
dark funnel descends. |
| Roaring
noise: The high winds of a tornado can cause a roar that
is often compared with the sound of a freight train. |
| Calm
behind the storm: Tornadoes generally occur near the
trailing edge of a thunderstorm. It is not uncommon to see clear,
sunlit skies behind a tornado. |
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SAFETY
DURING THE STORM |
If at home:
- Go
at once to the basement, storm cellar, or 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, 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.
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If at school or
work:
- 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, heavy table
or desk, and hold on to it.
- Use
arms to protect head and neck.
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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.
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If
in a car:
- 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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FOLLOWING
THE STORM
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| 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
building. Return home only when authorities say it is safe.
Use the telephone only for
emergency calls.
Clean up spilled medicines,
bleaches or gasoline & 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.
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Inspecting
utilities in a flood 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. If you can, turn off the gas at the outside main
valve and call the gas company from a neighbors 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 line
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.
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Fujita
Tornado Scale
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F-0:
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40-72 mph -
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chimney
damage, tree branches broken
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F-1:
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73-112 mph -
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mobile
homes pushed off foundation or overturned
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F-2:
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113-157 mph -
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considerable damage, mobile homes demolished, trees uprooted
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F-3:
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158-205 mph -
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roofs and walls torn down, trains overturned, cars thrown
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F-4:
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206-260 mph -
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well-constructed walls leveled
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F-5:
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261-318 mph -
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homes lifted off foundation and carried considerable distances, autos
thrown as far as 100 meters.
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