35 C ARICAD encourages you to become familiar with the specific terms that are used in official circles in relation to tropical storms and hurricanes. The more familiar you are with the meanings of the terms, the more confident you will be with your own Preparedness and the more likely you will be to help others to prepare. The following are among those terms: SOURCE – National Hurricane Centre – USA Advisory: Official information issued by tropical cyclone warning centres describing all tropical cyclone watches and warnings in effect along with details concerning tropical cyclone locations, intensity and movement, and precautions that should be taken. Advisories are also issued to describe: (a) tropical cyclones prior to issuance of watches and warnings and (b) subtropical cyclones. They are usually issued every six hours. Special advisories are issued when there is a significant change in storm-related weather conditions. Centre (Center): Generally speaking, the vertical axis of a tropical cyclone, usually defined by the location of minimum wind or minimum pressure. The cyclone centre position can vary with altitude. Cyclone: An atmospheric closed circulation rotating counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Eye: The roughly circular area of comparatively light winds that encompasses the centre of a severe tropical cyclone. The eye is either completely or partially surrounded by the eyewall cloud. Eyewall/Wall Cloud: An organised band or ring of cumulonimbus clouds that surround the eye, or light-wind canter of a tropical cyclone. Eyewall and wall cloud are used synonymously. Gale Warning: A warning of 1-minute sustained surface winds in the range 34 kit (39 mph or 63 km/hr) to 47 knots (54 mph or 87 km/hr) inclusive, either predicted or occurring and not directly associated with tropical cyclones. High Wind Warning: A high wind warning is defined as 1-minute average surface winds of 35 knots (40 mph or 64 km/hr) or greater lasting for 1 hour or longer, or winds gusting to 50 knots (58 mph or 93 km/hr) or greater regardless of duration that are either expected or observed over land. Hurricane/Typhoon: A tropical cyclone in which the maximum sustained surface wind (using the U.S. 1-minute average) is 64 knots (74 mph or 119 km/hr) or more. The term hurricane is used for Northern Hemisphere tropical cyclones east of the International Dateline to the Greenwich Meridian. The term typhoon is used for Pacific tropical cyclones north of the Equator west of the International Dateline. Hurricane Season: The portion of the year having a relatively high incidence of hurricanes. The hurricane season in the Atlantic, Caribbean, and Gulf of Mexico runs from June 1 to November 30. The hurricane season in the Eastern Pacific basin runs from May 15 to November 30. The hurricane season in the Central Pacific basin runs from June 1 to November 30. Hurricane Warning: A warning that sustained winds 64 kt (74 mph or 119 km/hr) or higher associated with a hurricane are expected in a specified coastal area in 24 hours or less. A hurricane warning can remain in effect when dangerously high water or a combination of dangerously high water and exceptionally high waves continue, even though winds may be less than hurricane force. Continues on next page
36 Publizr Home