Tropical Wave: A large low-pressure system in the tropics and subtropics.

Tropical Depression: A weak storm system with winds of 38 mph or less and rotary movement only on the water's surface.

Tropical Disturbance: A group of thunderstorms that moves together through the tropics for at least 24 hours, but with no noticeable circular motion.

Tropical Storm: A storm with distinct rotary movement and winds 39 to 74 mph.

Tropical Storm Watch: An advisory issued by the National Hurricane Center when tropical storm conditions, with winds of 39 to 73 mph, could threaten a coastal area within 24 to 36 hours.

Tropical Storm Warning: An advisory issued when winds of 39 to 73 mph are expected. If a hurricane is expected, tropical storm warnings probably will not be issued before hurricane warnings.

Hurricane Watch: An advisory issued when hurricane conditions are a threat within 24 to 36 hours. Chances are 1-in-3 the center part of the watch area will be hit. There's a 1-in-4 chance any location in the watch area will be hit, a 1-in-5 chance for the edges of the watch area.

Hurricane Warning: An advisory that says hurricane conditions are expected in a specific area within 24 hours. That means a 1-in-2 chance the central part of the warning area will be hit, a 1-in-3 chance for the edges of the warning zone. All areas in the warning zone are likely to be affected, even if the hurricane grazes by.

Storm Surge: The abnormally rapid and high rise in the sea into a wall or dome of water that is pushed onto shore by the high winds of the storm.
 

Hurricane: A circular windstorm in tropical or subtropical climates with a defined eye and winds of at least 74 mph. Tropical cyclones, the general term for all large-scale circular windstorms in the tropics and subtropics, are called hurricanes in the Atlantic Ocean, the Caribbean, Gulf of Mexico, eastern Pacific Ocean, and near Hawaii. Tropical cyclones in the north Pacific Ocean are called typhoons.
 

The Saffir-Simpson Hurricane Scale: The Saffir-Simpson Hurricane Scale is a 1-5 rating based on a hurricane's intensity with 1 being the weakest. The scale was designed by two South Floridians, Herbert Saffir, a Coral Gables engineer, and Robert Simpson, former director of the National Hurricane Center. This scale is used to provide an estimate of a storm's potential for flooding and property damage.

Category One Hurricane:

Winds 74-95 mph (64-82 kt or 119-153 kph).

Storm surge generally 4-5 ft above normal.

No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage.

Category Two Hurricane:

Winds 96-110 mph (83-95 kt or 154-177 kph).

Storm surge generally 6-8 feet above normal.

Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings.

Category Three Hurricane:

Winds 111-130 mph (96-113 kt or 178-209 kph).

Storm surge generally 9-12 ft above normal.

Some structural damage to small residences and utility buildings with a minor amount of curtain-wall failures. Damage to shrubbery and trees with foliage blown off trees and large tress blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Flooding near the coast destroys smaller structures with larger structures damaged by battering of floating debris. Terrain continuously lower than 5 ft above mean sea level may be flooded inland 8 miles (13 km) or more. Evacuation of low-lying residences with several blocks of the shoreline may be required.

Category Four Hurricane:

Winds 131-155 mph (114-135 kt or 210-249 kph).

Storm surge generally 13-18 ft above normal.

More extensive curtain-wall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km).

Category Five Hurricane:

Winds greater than 155 mph (135 kt or 249 kph).

Storm surge generally greater than 18 ft above normal.

Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required.