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What is a Hurricane?
A Hurricane is a type of tropical cyclone - the general term for all circulating weather systems (counter clockwise in the Northern Hemisphere) over tropical waters.
Classifying Tropical Cyclones
Tropical cyclones are classified as follows:
An organized system of clouds & thunderstorms with a defined circulation and maximum sustained winds of 38 mph. (33 knots or less).
An organized system of strong thunderstorms with a defined circulation & maximum sustained winds of 39 to 73 mph. (34-63 knots).
An intense tropical weather system with a well defined circulation and maximum sustained winds of 74 mph. (64 knots or higher). A Hurricane Watch means that conditions are possible in the area specified as a Watch Area, usually within 36 hours. A Hurricane Warning means that conditions are expected in the area specified as a Warning Area, usually within 24 hours.
Saffir Simpson Hurricane Scale
Storm surge is a large dome of water, often 50 to 100 miles wide that sweeps across the coastline near where a hurricane makes landfall. The surge of high water, topped by waves is devastating. The stronger the hurricane and the shallower the offshore water, the higher the surge will be. Along the immediate coast, storm surge is the greatest threat to life and property.
If the storm surge arrives at the same time as high tide, the water height will be even greater. Storm Tide is the combination of storm surge and normal astronomical tide. Over 6,000 were killed in the Galveston Hurricane of 1900, most by storm tide. Hurricane Hugo in 1989 generated a 20 foot storm tide in South Carolina.
Hurricane force winds, 74 mph. or more, can destroy poorly constructed buildings and mobile homes. Debris, such as signs, roofing materials, siding, and small items become flying missiles in hurricanes. Winds often stay above hurricane strength well inland. Power lines are knocked down. Trees break and fall and can cause massive destruction. High winds are very dangerous.
Widespread torrential rains often in excess of 6 inches can produce deadly and destructive floods. This is the major threat to areas well inland. Hurricanes Agnes (1972) fused with another storm system, producing floods in the Northeast U.S. which contributed to 122 deaths and 6.4 billion in damages.
Hurricanes also produce tornadoes, which add to the hurricane's destructive power. These tornadoes most often occur in thunderstorms embedded in rain bands well away from the center of the hurricane. However, they can also occur near the eye wall.