Terms and Signals

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Here are some of the definitions of terms and signals that you may be hearing during hurricane season:
TROPICAL DEPRESSION A low-pressure system or cyclone with sustained winds of less than 39 miles per hour (mph).

TROPICAL STORM A cyclone where winds range from 39 to 73 mph.

HURRICANE A tropical cyclone with winds of 74 mph or more. Torrential rains, destructive waves, and high waters known as storm surge, may create flood conditions in coastal and low-lying areas. More lives are claimed by storm surge and flooding in most parts of the world than by the winds of a hurricane. 

When a Tropical Depression forms, the NWS issues a series of advisories, which include watches and warnings, based on the strength and position of an approaching storm, as follows:

HURRICANE WATCH Issued by the NWS if hurricane conditions could possibly reach the islands within 48 hours. 

HURRICANE WARNING Issued by the NWS when dangerous hurricane conditions are expected to affect the islands within 36 hours or less. 

Remember, in our island environment, both winds and storm generated waves present significant hazards. Coastal flooding from the ocean often occurs in low-lying areas, and residents should refer to the phonebook yellow pages for information on Emergency Management evacuation zones (see Disaster Preparedness Guide). Torrential rains of tropical storms can also turn small streams into raging torrents, cause dangerous rock and mud slides, and flash flooding.