ingredients for a hurricane include a pre-existing weather disturbance, warm
tropical oceans, moisture, and relatively light winds aloft. If the right conditions
persist long enough, they can combine to produce the violent winds, incredible
waves, torrential rains, and floods we associate with this phenomenon.
year, an average of eleven tropical storms develop over the Atlantic Ocean, Caribbean
Sea, and Gulf of Mexico. Many of these remain over the ocean and never impact
the U.S. coastline. Six of these storms become hurricanes each year. In an
average 3-year period, roughly five hurricanes strike the US coastline, killing
approximately 50 to 100 people anywhere from Texas to Maine. Of these, two
are typically "major" or "intense" hurricanes
(a category 3 or higher storm on the Saffir-Simpson
is a Hurricane?
hurricane is a type of tropical cyclone, which is a generic term for a low pressure
system that generally forms in the tropics. The cyclone is accompanied by thunderstorms
and, in the Northern Hemisphere, a counterclockwise circulation of winds near
the earth's surface. Tropical cyclones are classified as follows:
A 1-minute average wind measured at about 33 ft (10 meters) above
1 knot = 1 nautical mile per hour or 1.15 statute miles per hour.
Abbreviated as "kt".
An organized system of clouds and thunderstorms with a defined surface circulation
and maximum sustained winds* of 38 mph (33 kt**) or less
An organized system of strong thunderstorms with a defined surface circulation
and maximum sustained winds of 39-73 mph (34-63 kt)
An intense tropical weather system of strong thunderstorms with a well-defined
surface circulation and maximum sustained winds of 74 mph (64 kt) or higher
Hurricanes are categorized according to the strength of their winds using
the Saffir-Simpson Hurricane Scale.
A Category 1 storm has the lowest wind speeds, while a Category 5 hurricane
has the strongest. These are relative terms, because lower category storms
can sometimes inflict greater damage than higher category storms, depending
on where they strike and the particular hazards they bring. In fact, tropical
storms can also produce significant damage and loss of life, mainly due to flooding.
When the the winds from these storms reach 39 mph (34 kts), the cyclones are
given names. Years ago, an international committee developed names for Atlantic
cyclones (The History of Naming Hurricanes).
In 1979 a six year rotating list of Atlantic storm names was adopted
alternating between male and female hurricane names. Storm names are used to
facilitate geographic referencing, for warning services, for legal issues, and
to reduce confusion when two or more tropical cyclones occur at the same time.
Through a vote of the World Meteorological Organization Region IV Subcommittee,
Atlantic cyclone names are retired usually when hurricanes result in substantial
damage or death or for other special circumstances. The names assigned for the
next several seasons are shown below.
for Atlantic Basin Tropical Cyclones
TRACKING CHART (0.7mb)
AIM A HURRICANE (0.4mb)
HURRICANES FOR KIDS
- Know if you
live in an evacuation area. Know your home's vulnerability to storm surge,
flooding and wind. Have a written plan based on this knowledge.
- At the beginning
of hurricane season (June 1st), check the supplies for your disaster
supply kit, replace batteries and use food stocks on a rotating basis.
- During hurricane
season, monitor the tropics.
- Monitor NOAA
Weather Radio. It is an excellent / official source for real-time weather
information and warnings.
- If a storm threatens,
heed the advice from local authorities. Evacuate if ordered.
- Execute your
vs. WARNING - KNOW THE DIFFERENCE
HURRICANE WATCH issued for your part of the coast indicates the possibility
that you could experience hurricane conditions within 36 hours.
This watch should trigger your family's disaster plan, and protective measures
should be initiated, especially those actions that require extra time such
as securing a boat, leaving a barrier island, etc.
issued for your part of the coast indicates that sustained
winds of at least 74 mph are expected within 24 hours or less.
this warning has been issued, your family should be in the process of completing
actions and deciding the safest location to be during the storm.