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Tornado Myths and Facts
“When confronted by a tornado warning, you should open all the windows in
your house to equalize the pressure.”
MYTH: This just wastes valuable time. Don’t worry about equalizing the
pressure, the roof ripping off and the pickup truck smashing through the
front wall will equalize the pressure for you.
“I live in a big city, a tornado wouldn’t hit a big city.”
MYTH: Tornadoes have hit several large cities, including Dallas, Oklahoma
City, Wichita Falls, St. Louis, Miami, and Salt Lake City. In fact, an urban
tornado will have a lot more debris to toss around than a rural twister.
A tornado approaches downtown Dallas, TX on 02 April, 1957
NOAA library page
The path of the May 3, 1999 F5 tornado that tore through downtown Oklahoma
City
From KFOR-TV, Oklahoma
“Tornadoes don’t happen in the mountains.”
MYTH: Tornadoes do occur in the mountains. Damage from an F3 tornado was
documented above 10,000 feet, and a hiker in the mountains of Utah
photographed a weak tornado in the mountains.
“Tornadoes may occur in the middle of the night and even during the winter.”
FACT: Although the likelihood is lower at night and during colder months,
tornadoes have caused death and destruction during these times of day and
year. Violent tornadoes, while very unlikely during the winter months, do
occasionally occur at night. When severe weather is forecast, ensure your
NOAA weather radio is on and working properly before you go to bed.
“My city doesn’t get tornadoes because it is protected by a river.”
MYTH: Many tornadoes have crossed rivers and even gone on to cause
widespread damage to riverside cities. For example, the Nachez, Mississippi
tornado of 1840
tracked
directly down the Mississippi River, killing hundreds, mostly on the water.
view the photo here:
http://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-clima
tology
Others have crossed large rivers without losing speed (they momentarily
became water spouts) and devastated cities that folklore had thought immune
to tornadoes. An example was the Waco, TX tornado of 1953
that
crossed the Brazos River, seen at this link.
http://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-clima
tology
or the Great St. Louis Cyclone of 1896
that
jumped the Mississippi River. Seen at this link.
http://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-clima
tology
“Tornadoes have picked people and items up, carried them some distance and
then set them down without injury or damage.”
FACT: People and animals have been transported up to a quarter mile or more
without serious injury. Fragile items, such as sets of fine china, or
glass-ware have been blown from houses and recovered, miles away, without
any damage. However, given the quantity of airborne debris, these
occurrences are the exception, rather than the norm.
“Hiding under a freeway overpass will protect me from a tornado.”
MYTH: While the concrete and re-bar in the bridge may offer some protection
against flying debris, the overpass also acts as a wind tunnel and may
actually serve to collect debris. When you abandon your vehicle at the
overpass and climb up the sides, you are doing two things that are
hazardous. First, you are blocking the roadway with your vehicle. When the
tornado turns all the parked vehicles into a mangled, twisted ball and
wedges them under the overpass, how will emergency vehicles get through?
Second, the winds in a tornado tend to be faster with height. By climbing up
off the ground, you place yourself in even greater danger from the tornado
and flying debris. When coupled with the accelerated winds due to the wind
tunnel (Venturi Effect), these winds can easily exceed 300 mph.
Unfortunately, at least three people hiding under underpasses during
tornadoes have already been killed, and dozens have been injured by flying
debris. If you realize you won’t be able to outrun an approaching tornado,
you are much safer to abandon your vehicle, and take shelter in a road-side
ditch or other low spot (see Tornado Safety
).
http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadosafety.html#safety
For more information on the use of highway overpasses for shelter, please
see this NWS discussion on highway overpasses
.
http://www.srh.noaa.gov/oun/?n=safety-overpass-slide01
Note: If a highway overpass is your only shelter option, only consider it if
the overpass has sturdy roadway supports, next to which (at ground level)
you can take shelter. Avoid the smooth concrete, support-less spans at all
costs.
“I can outrun a tornado, especially in a vehicle.”
MYTH: Tornadoes can move at up to 70 mph or more and shift directions
erratically and without warning. It is unwise to try to outrace a tornado.
It is better to abandon your vehicle and seek shelter immediately.
“While there is no such thing as a category 6 hurricane (the Saffir-Simpson
Hurricane Scale only goes to
category 5), there can be an F6 tornado.”
This tornado scale can be seen here:
http://www.nhc.noaa.gov/aboutsshws.php
FACT: The Fujita Tornado Damage Intensity Scale
actually goes up to F12!
Check out the photo here:
http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/fujita.html
The F12 level only begins at wind speeds exceeding Mach 1.0 (or around 738
mph at -3]]>
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