Hurricane Terms You Should Know

A hurricane is a severe tropical storm characterized by high winds that blow in a large spiral around a relatively calm center, or "eye." Understanding the terminology used by weather forecasters can help you be prepared if a hurricane is coming your way. For an explanation of common hurricane terms, read on.

Tropical waves, disturbances, and depressions: When a trough of low pressure occurs in the trade-wind easterlies. It can develop into a tropical disturbance, a moving area of thunderstorms in the tropics that remains for 24 hours or longer. A tropical disturbance can develop into tropical depression, which is a circulation at the surface with a maximum constant wind speed of 38 mph. A tropical depression can accellerate to become a tropical storm.

Tropical storms: This is a distinct circulation with a wind speed of 39 to 74 mph. Tropical storms often develop into hurricanes. A tropical storm watch is issued for coastal areas when there is a threat of a tropical storm within 24 to 36 hours. A tropical storm warning is issued when the threat is within 24 hours.

Hurricane: A circulation of air with a constant wind speed of 74 mph or greater. The intensity of a hurricane is measured on the Saffir-Simpson Scale, which ranks hurricanes on a scale of 1 to 5 according to wind speed, barometric pressure, storm surge, and damage potential. A hurricane watch is an advisory issued for coastal areas when the threat of hurricane conditions is within 24 to 36 hours. A hurricane warning is issued when hurricane-force winds will occur within 24 hours or less. Take shelter.

Hurricane local statement: Listen to the news for a hurricane local statement, a public release issued by the National Weather Service that details the potential impact of a hurricane on a local area. It often contains important information on weather conditions, evacuation instructions, and other safety precautions you should take.

Eye and eye wall: The eye of the hurricane is the relatively calm center. It is surrounded by the eye wall, an area of very intense winds.

Strike probabilities: This is issued as a percentage and indicates the highest probability of a land strike for a hurricane.

Major hurricane: A hurricane with a ranking of 3 or higher on the Saffir-Simpson Scale. Evacuate as quickly as you can.

Hurricane season: The time of year when a hurricane is most likely to occur. In the Atlantic, Caribbean, Gulf of Mexico, and Central Pacific the season runs from June to December. In the Eastern Pacific, it runs from mid-May to December.

Storm surge and storm tide: An abnormal rise in sea level accompanying a hurricane. A storm tide is the actual level of sea water resulting from the astronomic tide combined with the storm surge.

Cyclone: An atmospheric, closed circulation rotating counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere.

Gale warning and high-wind warning: A gale warning is a warning of one-minute sustained surface winds in the range of 39 mph to 54 mph not associated with a tropical storm. A high-wind warning is defined as one-minute surface winds of 40 mph or greater lasting for one hour or longer, or winds gusting to 58 mph or greater regardless of duration.