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Storm Prediction Center

Hurricanes, Typhoons and
Tropical Cyclones

Most of the information provided here was taken from The Red Cross, Hurricanes: A Preparedness Guide, and from information provided by the Storm Prediction Center.

What is a hurricane?

A hurricane is a type of tropical cyclone-the general term for all circulating weather systems (counterclockwise in the Northern hemisphere) over tropical waters. Tropical cyclones are classified as follows:

Tropical Depression - An organized system of clouds and thunderstorms with a defined circulation and maximum sustained winds of 38 mph (33 knots) or less.

Tropical Storm - An organized system of strong thunderstorms with a defined circulation and maximum sustained winds of 39 to 73 mph (34-63 knots).

Hurricane - An intense tropical weather system with a well defined circulation and maximum sustained winds of 74 mph (64 knots) or higher. In the western Pacific, hurricanes are called "typhoons," and similar storms in the Indian Ocean are called "cyclones."

Hurricanes are products of the tropical ocean and atmosphere. Powered by heat from the sea, they are steered by the easterly trade winds and the temperate westerlies as well as by their own ferocious energy. Around their core, winds grow with great velocity, generating violent seas. Moving ashore, they sweep the ocean inward while spawning tornadoes and producing torrential rains and floods. Each year on average, ten tropical storms (of which six become hurricanes) develop over the Atlantic Ocean, Carribean Sea, or Gulf of Mexico. Many of these remain over the ocean. However, about five hurricanes strike the United States coastline every 3 years. Of these five, two will be major hurricanes (category 3 or greater on the Saffir-Simpson Hurricane Scale).

Saffir-Simpson Hurricane Scale.

Category Sustained Winds (MPH) Damage
1 74-95 Minimal
2 96-110 Moderate
2 111-130 Extensive
4 131-155 Extreme
5 >155 Catastrophic

Population Growth

The United States has a significant hurricane problem. There are now some 45 million permanent residents along the hurricane-prone coastline, and the population is still growing. The most rapid growth has been in the sunbelt from Texas through the Carolinas. Florida, where hurricanes are most frequent, leads the Nation in new residents. In addition to the permanent residents, the holiday, weekend, and vacation populations swell in some coastal areas 10- to 100-fold.

Areas at Risk

Coastal Areas and Barrier Islands

Top Ten Most Expensive Atlantic Coast Cyclones on the US mainland.

RANKING HURRICANE YEAR CATEGORY DAMAGE (U.S.)
1. ANDREW (SE FL/SE LA) 1992 4 $26,500,000,000
2. HUGO (SC) 1989 4 $7,000,000,000
3. FRAN (NC) 1996 3 $3,200,000,000
4. OPAL (NW FL/AL) 1995 3 $3,000,000,000
5. FREDERIC (AL/MS) 1979 3 $2,300,000,000
6. AGNES (NE U.S.) 1972 1 $2,100,000,000
7. ALICIA (N TX) 1983 3 $2,000,000,000
8. BOB (NC and NE U.S.) 1991 2 $1,500,000,000
8. JUAN (LA) 1985 1 $1,500,000,000
10. CAMILLE (MS/AL) 1969 5 $1,420,700,000

This information is taken from The National Oceanic and Atmospheric Administration's The Deadliest, Costliest, and Most Intense United States hurricanes of this century (and other frequently requested hurricane facts) [NOAA Technical Memorandum NWS TPC-1] updated in February, 1997.

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Related Links

If you would like more information about Hurricanes, Typhoons and Tropical Cyclones, please visit these resources.

An extensive  list of Questions and Answers about Hurricanes by Dr. Chris Landsea.

Climate Prediction Center
The mission of the Climate Prediction Center is to maintain a continuous watch on short-term climate fluctuations and to diagnose and predict them. These efforts are designed to assist agencies both inside and outside the federal government in coping with such climate related problems as food supply, energy allocation, and water resources.

Hail Size and Wind Speed Tables
From National Weather Service Pleasant Hill (MO).

Hurricanes: A Preparedness Guide

Interactive National Map of Watches and Warnings from Texas A&M.

Latest advisories from the National Hurricane Center -- Atlantic and East Pacific.

Latest Weather Warnings Across the Country
From National Weather Service IWIN page.

National Severe Storms Laboratory 
Scientific research into severe and hazardous weather.

National Weather Service

Severe and Unusual Weather Terminology
A glossary of some technical meteorological terms.

Storm Prediction Center
SPC monitors and forecasts severe and non-severe thunderstorms, tornadoes, and other hazardous weather phenomena across the conterminous U.S. -- 24 hours a day, every day of the year. They used to be known as the SEvere Local Storms (SELS) unit of the National Severe Storms Forecast Center (NSSFC).

Storm Track
Non-profit magazine devoted to severe storms.

Texas Severe Storms Association

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Automotive Risk Management & Insurance Services, Inc.
2087 Grand Canal Blvd., Suite 12, Stockton, CA 95207.
Mailing Address: P.O. Box 70334 Stockton, CA 95267.
Phone: (209) 473-8937, Fax: (209) 472-8692, e-mail:mmcdougal@armonline.com
California Insurance License No. OB89379

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Last modified: 12/16/02