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Hurricane Terminology

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What is a Hurricane?

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A hurricane is a type of tropical cyclone, which is a generic term for a low-pressure system that generally forms in the tropics. The cyclone is accompanied by thunderstorms and, in the Northern Hemisphere, a counterclockwise circulation of winds near the earth's surface.

Tropical cyclones are classified as follows:

Tropical Depression - An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 mph or less.  A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 38 mph or less.

Tropical Storm - An organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds of 39-73 mph.   A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) ranges from 39 mph to 73 mph.

Hurricane - An intense tropical weather system of strong thunderstorms with a well-defined surface circulation and maximum sustained winds of 74 mph or higher.

The 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.

Saffir-Simpson Hurricane Scale - hurricanes are categorized according to the strength of their winds using the Saffir-Simpson Hurricane Scale. A Category 1 storm has the lowest wind speeds, while a Category 5 hurricane has the strongest. These are relative terms, because lower category storms can sometimes inflict greater damage than higher category storms, depending on where they strike and the particular hazards they bring. In fact, tropical storms can also produce significant damage and loss of life, mainly due to flooding.

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Tropical Storm — winds 39-73 mph
Category 1 Hurricane — winds 74-95 mph
Category 2 Hurricane — winds 96-110 mph
Category 3 Hurricane — winds 111-130 mph
Category 4 Hurricane — winds 131-155 mph
Category 5 Hurricane — winds 156 mph and up

 

Tropical Storm Watch - An announcement that sustained winds of 34 to 63 knots (39 to 73 mph or 63 to 118 km/hr) are possible within the specified area within 48 hours in association with a tropicalsubtropical, or post-tropical cyclone.

Tropical Storm Warning - An announcement that sustained winds of 34 to 63 knots (39 to 73 mph or 63 to 118 km/hr) are expected somewhere within the specified area within 36 hours in association with a tropicalsubtropical, or post-tropical cyclone.

Hurricane Watch  - An announcement that sustained winds of 64 knots (74 mph or 119 km/hr) or higher are possible within the specified area in association with a tropical,subtropical, or post-tropical cyclone. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical storm force winds.

Hurricane Warning - An announcement that sustained winds of 64 knots (74 mph or 119 km/hr) or higher are expected somewhere within the specified area in association with a tropicalsubtropical, or post-tropical cyclone. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds. The warning can remain in effect when dangerously high water or a combination of dangerously high water and waves continue, even though winds may be less than hurricane force.

Storm Surge - An abnormal rise in sea level accompanying a hurricane or other intense storm, and whose height is the difference between the observed level of the sea surface and the level that would have occurred in the absence of the cyclone. Storm surge is usually estimated by subtracting the normal or astronomic high tide from the observed storm tide.

Fort Lauderdale/ Broward County Hurricane Evacuation Map/ Regional Shelters – Those persons located in low lying areas or near tidal bodies of water should seek shelter elsewhere if conditions warrant. ALL mobile home residents must evacuate in Plan A and B. In addition, mobile home residents may be ordered to evacuate if tropical storm conditions warrant.

Contact
Domestic Preparedness and Emergency Management Bureau
2200 Executive Airport Way
Fort Lauderdale, FL 33309
Phone: 954-828-6700
Email: FTL.EM@fortlauderdale.gov.