All Hurricanes are dangerous, but some are more so than others. The way storm surge, wind and other factors combine determines the hurricanes destructive power.

To make comparisons easier and to make the predicted hazards of approaching hurricanes clearer to emergency forces, National Oceanic and Atmospheric Administration's hurricane forecasters use a disaster-potential scale which assigns storms to five categories. This can be used to give an estimate of the potential property damage and flooding expected along the coast with a hurricane.

 

Category	Definition	Effects
One	Winds 74-95 mph	No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal road flooding and minor pier damage
Two	Winds 96-110 mph	Some roofing material, door, and window damage to buildings. Considerable damage to vegetation, mobile homes, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of center. Small craft in unprotected anchorage's break moorings.
Three	Winds 111-130 mph	Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain continuously lower than 5 feet ASL may be flooded inland 8 miles or more.
Four	Winds 131-155 mph	More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach. Major damage to lower floors of structures near the shore. Terrain continuously lower than 10 feet ASL may be flooded requiring massive evacuation of residential areas inland as far as 6 miles.
Five	Winds greater than 155 mph	Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Major damage to lower floors of all structures located less than 15 feet ASL and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5 to 10 miles of the shoreline may be required.

 

Example

Category	Sustained Winds MPH	Damage	Examples
1	74-95	Minimal	Florence (1988) LA, Charley (1988) NC
2	96-110	Moderate	Kate 1985, Bob 1991
3	111-130	Extensive	Alicia 1983 TX
4	131-155	Extreme	Andrew 1992 FL, Hugo 1989 NC
5	155	Catastrophic	Camille 1969 MS, Labor Day Hurricane 1935 Fl Keys

 

 

"Terms to Know"

 

By international agreement, tropical cyclone is the general term for all cyclone circulation's originating over tropical waters, classified by form and intensity as follows:

	Tropical disturbance: A moving area of thunder storms in the Tropics that maintains its identity for 24-hours or more. A common phenomenon in the tropics.
	Tropical depression: Rotary circulation at surface highest constant wind speed 38 miles per hour (33 knots).
	Tropical storm: Distinct rotary circulation, constant wind speed ranges 39-73 miles per hour (34-63 knots).
	Hurricane: Pronounced rotary circulation, constant wind speed of 74 miles per hours (64 knots) or more.

Small craft cautionary statements. When a tropical cyclone threatens a coastal area, small craft operators are advised to remain in port or not to venture into the open sea.

Gale Warnings may be issued when winds of 39- 54 miles an hour (34-47 knots) are expected. Storm Warnings may be issued when winds of 55- 73 miles an hour (48-63 knots) are expected. If a hurricane is expected to strike a coastal area, gale or storm warnings will not usually precede hurricane warnings.

A Hurricane Watch is issued for a coastal area when there is a threat of hurricane conditions within 24-36 hours.

A Hurricane Warning is issued when hurricane conditions are expected in a specified coastal area in 24 hours or less. Hurricane conditions include winds of 74 miles an hour (64 knots) and/or dangerously high tides and waves. Actions for protection of life and property should begin immediately when the warning is issued.

	Flash Flood Watch means a flash flood is possible in the area; stay alert.
	Flash Flood Warning means a flash flood is imminent; take immediate action.

Tornadoes spawned by hurricanes sometimes produce severe damage and casualties. If a tornado is reported in your area, a warning will be issued.