Coastal Chatham Severe Watches & Warnings NOAA Weather Radio

Public Information Statement
Statement as of 7:00 am EDT on May 24, 2015

... National hurricane preparedness week begins today...

Hurricane preparedness week will be observed today through Saturday
may 30. The Atlantic hurricane season officially begins June 1. Partners
such as the National Weather Service... emergency management and the
American Red Cross all agree that preparedness is the key to
minimizing property damage and preventing loss of life. This annual
event provides an opportunity to remind everyone about the numerous
hazards associated with tropical cyclones and provide tips on how to
prepare for the upcoming hurricane season. Today we will discuss the
basics of tropical cyclones.

Tropical cyclone classification...

Tropical disturbance... a discrete tropical system of clouds and
thunderstorms lacking attributes of a tropical depression.

Tropical depression... an organized system of clouds and
thunderstorms with a defined surface circulation and maximum
sustained surface winds of 38 mph or less.

Tropical storm... an organized system of strong thunderstorms with
a defined surface circulation and maximum sustained surface winds
of 39 to 73 mph.

Hurricane... an intense tropical weather system of strong
thunderstorms with a well-defined surface circulation and maximum
sustained surface winds of 74 mph or greater.

Major hurricane... a category 3-5 hurricane.

Subtropical cyclone... low pressure system which exhibits
characteristics of a tropical cyclone and an extratropical low
pressure. If sufficiently strong, these systems are named and can
create dangerous conditions.

Post tropical cyclone... former tropical cyclone which no longer
exhibits tropical charactersistics.

Hurricanes are categorized according to the strength of their
winds based on the Saffir-Simpson hurricane wind scale. A category
1 storm has the lowest wind speeds... while a category 5 has the
strongest. However... these are relative terms... because lower
category storms can sometimes produce greater storm surge and
inflict greater damage than higher category storms.

Tropical cyclones are given names when they reach tropical storm
strength. A six year rotating list of storm names determined by the
world meteorological organization alternates between male and
female names. When a tropical cyclone produces substantial damage
and/or fatalities... the name of that tropical cyclone is retired.
Notable retired names include Camille... Hugo... Andrew... Katrina and

Tropical cyclone development...

Some of the ingredients for tropical cyclones include a pre-existing
weather disturbance... warm water of considerable depth... abundant moisture
and relatively light winds in the higher levels of the atmosphere.

Tropical cyclone climatology...

Each year... an average of 12 tropical storms develop over the Atlantic
Basin... which includes the Atlantic Ocean... the Caribbean Sea and the
Gulf of Mexico. Of these... 6 become hurricanes... with 2 of these
becoming major hurricanes /category 3 or greater/. While most tropical
cyclones remain over the open water and never impact land... roughly 5
hurricanes will strike the United States coastline from Texas to Maine
on average every 3 years.

For additional information on hurricanes visit the following websites...

National Hurricane Center... www.Hurricanes.Gov

National Weather Service Charleston... www.Weather.Gov/chs/tropical

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