Forecasters use a “disaster-potential” scale from 1 through 5 to categorize a hurricane’s strength based on its present intensity. Also known as the “Saffir-Simpson Hurricane Scale”, 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 and the shape of the coastline, in the landfall region.*
TROPICAL STORM
Wind Speed: 39-73 mph (34-63 kt)
Storm Surge: Negligible
Damage Potential: Isolated damage for winds below 50 mph. Above 50 mph, expect minor damage to buildings of light material and attached corrugated sheet metal. Moderate damage to banana and papaya trees. Small branches are blown from other trees.
CATEGORY 1(Weak) Hurricane Iwa, 1982
Wind Speed: 74-95 mph (64-82 kt or 119-153 km/hr)
Storm Surge: 4-5 ft
Damage Potential: Minimal damage to vegetation. No real damage to other structures. Some damage to poorly constructed signs. Low-lying coastal roads inundated, minor pier damage, some small craft in exposed anchorage torn from moorings.
CATEGORY 2 (Moderate)
Wind Speed: 96-110 mph (83-95 kt or 154-177 km/hr)
Storm Surge: 6-8 ft
Damage Potential: Considerable damage to vegetation; some trees blown down. Major damage to exposed mobile homes. Moderate damage to houses. Considerable damage to piers; marinas flooded. Small craft in unprotected anchorages torn from moorings. Evacuation from some shoreline residences and low-lying areas required.
CATEGORY 3 (Strong) Hurricanes Jeanne & Ivan, 2004
Wind Speed: 111-130 mph (96-113 kt or 178-209 km/hr)
Storm Surge: 9-12 ft
Damage Potential: Large trees blown down. Mobile homes destroyed. Extensive damage to small buildings. Poorly constructed signs blown down. Serious coastal flooding; larger structures near coast damaged by battering waves and floating debris.
CATEGORY 4 (Very Strong) Hurricane Iniki, 1992
Wind Speed: 131-155 mph (114-135 kt or 210-249 km/hr)
Storm Surge: 13-18 ft
Damage Potential: All signs blown down. Complete destruction of mobile homes. Extreme structural damage. Major damage to lower floors of structures due to flooding and battering by waves and floating debris. Major erosion of beaches.
CATEGORY 5 (Catastrophic) Hurricanes Andrew, 1992 & Wilma, 2005
Wind Speed: Greater than 155 mph (135 kt or 249 km/hr)
Storm Surge: Greater then 18 ft
Damage Potential: Catastrophic building failures. Devastating damage to roofs of buildings. Small buildings overturned or blown away.
*Source: Pacific Disaster Center.