Tornadoes occur in many
parts of the world. However, the most destructive ones are found in the
States east of the Rocky Mountains. Peak tornado months in the
southern states are March through May,
while peak months in the northern states are during the summer.
Tornadoes are most
likely to occur between 3:00 and 9:00 p.m. but have been known to occur
at all hours
of the day or night. 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
The most violent tornadoes are capable of tremendous destruction with
wind speeds of 250 miles per hour or
more. Paths of damage can be in excess of one mile wide and fifty miles
long. Once a tornado in Broken
Bow, Oklahoma, carried a motel sign 30 miles and dropped it in Arkansas!
conditions consistent with thunderstorm activity produce tornadoes.
develop in warm, moist air in advance of eastward moving cold fronts.
These thunderstorms often produce
large hail, strong winds, and tornadoes.
develop, a change in wind direction and an increase in wind speed create
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.
Tornadoes take on many
shapes and sizes. They are categorized as weak, strong, or violent.
tornadoes account for 69% of all tornadoes. Their lifetime is one to
ten minutes, with winds less than 110
miles per hour. Strong tornadoes account for 29% of all tornadoes.
They may last twenty minutes or longer,
with winds 110 – 205 miles per hour. Violent tornadoes account for only
2% of all tornadoes, but are the
cause of 70% of all tornado deaths. These tornadoes can exceed one hour
in length, with winds greater than
205 miles per hour.
There are many myths
surrounding tornadoes and tornado safety. One is that areas near
rivers, lakes, and
mountains are safe form tornadoes. The fact is 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 foot mountain.
Another common myth
is that windows should be opened before a tornado approaches to equalize
pressure. Opening windows is not a good idea. It allows damaging winds
to enter the structure. If a tornado
is coming your way, leave your windows alone and quickly get to a safe