Tropical Storm Centre: Saffir-Simpson Hurricane Scale

Saffir-Simpson Hurricane Scale

The Saffir-Simpson Hurricane Scale is a 1-5 rating based on a hurricane's present intensity. This is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf in the landfall region.

Category	Criteria
One	Winds 119-153 km/hr. Storm surge generally >1.2 metres. 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.
Two	Winds 154-177 km/hr. Storm surge generally >1.8 metres. 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 centre. Small craft in unprotected anchorages break moorings.
Three (major hurricane)	Winds 178-209 km/hr. Storm surge generally >2.7 metres. Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Damage to shrubbery and trees with foliage blown off trees and large trees 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 centre of the hurricane. Flooding near the coast destroys smaller structures with larger structures damaged by battering from floating debris. Terrain continuously lower than 1.5 metres above mean sea level may be flooded inland 13 km or more. Evacuation of low-lying residences with several blocks of the shoreline may be required.
Four (major hurricane)	Winds 210-249 km/hr. Storm surge generally >4 metres. More extensive curtainwall 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 centre of the hurricane. Major damage to lower floors of structures near the shore. Terrain lower than 3 metres above sea level may be flooded requiring massive evacuation of residential areas as far inland as 10 km.
Five (major hurricane)	Winds greater than 249 km/hr. Storm surge generally >5.5 metres. 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 centre of the hurricane. Major damage to lower floors of all structures located less than 4.5 metres above sea level and within 457 metres of the shoreline. Massive evacuation of residential areas on low ground within 8-16 km of the shoreline may be required.