A hurricane is a type of tropical cyclone, the general term for all circulating weather systems over tropical waters counter-clockwise in the Northern Hemisphere). 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.”
Hurricane winds blow in a large spiral around a relatively calm center known as the “eye.” The “eye” is generally 20 to 30 miles wide, and the storm may have a diameter of 400 miles across. As a hurricane approaches, the skies will begin to darken and winds will grow in strength. A hurricane can bring torrential rains, high winds, and storm surge as it nears land. A single hurricane can last more than two weeks over open waters and can run a path across the entire length of the eastern seaboard.
More dangerous than the high winds of a hurricane is the storm surge–a dome of ocean water that can be 20 feet high at its peak and 50 to 100 miles wide. The surge can devastate coastal communities as it sweeps ashore. In recent years, the fatalities associated with storm surge have been greatly reduced as a result of better warning and preparedness within coastal communities.
Most deaths due to tropical cyclones are flood-related. Inland flooding is a common occurrence with hurricanes and tropical storms. Torrential rains from decaying hurricanes and tropical storms can produce extensive urban and river flooding. Winds from these storms located offshore can drive ocean water up the mouth of rivers, compounding the severity of inland flooding. Inland streams and rivers can flood and trigger landslides. In addition, hurricanes can spawn tornadoes, which add to the destructiveness of the storm.
The Saffir-Simpson Hurricane Scale is a 1-5 “Category” rating based on the hurricane’s present intensity. This is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall.
TROPICAL STORM WATCH: Tropical Storm conditions are possible in the specified area of the Watch, usually within 36 hours.
TROPICAL STORM WARNING: Tropical Storm conditions are expected in the specified area of the Warning, usually within 24 hours.
HURRICANE WATCH: Hurricane conditions are possible in the specified area of the Watch, usually within 36 hours. During a Hurricane Watch, prepare to take immediate action to protect your family and property in case a Hurricane Warning is issued.
HURRICANE WARNING: Hurricane conditions are expected in the specified area of the Warning, usually within 24 hours. Complete all storm preparations and evacuate if directed by local officials.