Tropical System vs. Hurricane

Tropical depressions and storms are organized systems of clouds and thunderstorms with defined surface circulations. In a tropical depression, winds do not exceed 38 miles per hour. In a tropical storm, winds do not exceed 73 miles per hour. However, these systems should be taken seriously. They can bring heavy rain and localized flooding – and can quickly intensify in strength.

Once a tropical system's winds reach 74 miles per hour, the storm becomes a hurricane. Hurricane strength is measured from 1 to 5 on the Saffir Simpson Hurricane Scale (See chart at right).

Watch vs. Warning

A tropical storm watch means tropical storm conditions are possible within 36 hours. A tropical storm warning means tropical storm conditions are expected within 24 hours. A hurricane watch means hurricane conditions are possible within 36 hours. A hurricane warning means hurricane conditions are expected within 24 hours.

Weather conditions can change quickly, so stay informed. Official bulletins will be available from the National Hurricane Center Web site www.nhc.noaa.gov, as well as local TV and radio stations.

Saffir Simpson Hurricane Scale

Category 1 Category 2 Category 3 Category 4 Category 5 Amount of Expected Damage Minimal. Damage to shrubs, trees and mobile homes. Little or no building damage. May see some coastal flooding Moderate. Some damage to roofs, windows and doors. Downed trees and signs. Considerable damage to vegetation and mobile homes. Extensive. Some structural damage to residences and buildings. Major damage to mobile homes, trees, vegetation and signage. Coastal flooding. Extreme. Major damage to some buildings. Mobile homes destroyed. Inland flooding possible. Catastrophic. Major roof and structure failures on many residences. Some complete building failures. Major flooding. Barometric Pressure 28.94 inches 28.50 to 28.93 inches 27.91 to 28.49 inches 27.17 to 27.90 inches Less than 27.17 inches Winds 74 to 95 miles per hour. 96 to 110 miles per hour. 111 to 130 miles per hour. 131 to 155 miles per hour. In excess of 155 miles per hour. Expected Storm Surge 6 to 8 feet 6 to 8 feet 9 to 12 feet 13 to 18 feet Higher than 18 feet