Hurricanes and Tornadoes
Hurricanes
One of the most dramatic, damaging, and potentially deadly events
that occur in this country is a hurricane.
Hurricanes are products of the tropical ocean and atmosphere.
Powered by heat form the sea, they are steered erratically by the
easterly trade winds and the temperate westerly winds, as well as by
their own energy. As they move ashore, they bring with them a
storm surge of ocean
water along the coastline, high winds, tornadoes, and both torrential
rains and flooding.
Each year on average, ten tropical storms develop over the Atlantic
Ocean, Caribbean Sea, or Gulf of Mexico. About six of these will
strengthen enough to become hurricanes. Many of these remain over the
ocean with little or no impact on the continental United States.
However, about five hurricanes strike the United States coastline
every 3 years. Of these five, two will be major hurricanes measuring a
category 3 or higher (defined as having winds above 111 miles per
hour) on the Saffir-Simpson Scale. These storms can end up costing our
nation millions, if not billions, of dollars in damages.
During a hurricane, homes, businesses, public buildings, and
infrastructure may be damaged or destroyed by high winds and high
waves. Debris can break windows and doors, allowing high winds and
rain inside the home. Roads and bridges can be washed away by flash
flooding, or can be blocked by debris. In extreme storms (such as
Hurricane Andrew), the force of the wind alone can cause tremendous
devastation, as trees and power lines topple and weak elements of
homes and buildings fail. And these losses are not limited to the
coastline -- they can extend hundreds of miles inland, under the right
conditions.
Fortunately, there are a variety of measures that can be taken --
both at the individual and community levels -- to reduce your
vulnerability to hurricane hazards. Simple construction measures, such
as the use of storm shutters over exposed glass, and the addition of
hurricane straps to hold the roof of a structure to its walls and
foundation, have proven highly effective in lowering damages when
hurricanes strike. In addition, more complex mitigation measures can
be pursued to further reduce a property's susceptibility. For example,
coastal homes and businesses can be elevated to permit coastal storm surge to pass
under living and working spaces.
Communities can further reduce their vulnerability to hurricanes
through the adoption and enforcement of wind- and flood-resistant
building codes. Sound land-use planning can also ensure that
structures are not built in the highest hazard areas.
Tornadoes
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.
Examples of Mitigation Techniques
Hurricanes and tornadoes both have in common very high winds and
the associated damage. After Hurricane Andrew, a team of experts
examined homes that had failed and ones that had survived. They found
four areas that should be checked for weakness--the roof, windows,
doors, and if you have one, garage door. Some steps can be taken by
most homeowners to reduce the vulnerability of homes to high winds.
Others should only be done by an experienced builder. You will find
more information about how to prepare your family, home or business
for hurricanes and tornadoes at this Web site. You may also obtain
more information from you State office of emergency services, the
nearest Federal Emergency Management Agency Regional Office, and your
local office of the American
Red Cross.
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