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Saffir-Simpson Hurricane Scale
On May 15, 2012, there will be minor modifications made to the Saffir-Simpson Hurricane Wind Scale Thresholds for Categories 3, 4 and 5. These changes have been reflected in the documentation below. Please see the Public Information Statement issued March 1, 2012 for more details.
The Saffir-Simpson Hurricane Wind Scale for Hawaii
The Saffir-Simpson Hurricane Wind Scale for Hawaii is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The scale provides examples of the type of damages and impacts in Hawaii associated with winds of the indicated intensity. In general, damages rise by about a factor of four for every category increase. The maximum sustained surface wind speed (peak 1-minute wind at 10 m [33 ft]) is the determining factor in the scale. The historical examples provided in each of the categories correspond with the intensity of the hurricane at the time of landfall or closest approach in the location experiencing the strongest winds, which does not necessarily correspond with the peak intensity reached by the system during its lifetime. The scale does not address the potential for such other hurricane-related impacts as coastal inundation, waves, and storm surge, rainfall-induced floods, and tornadoes. The wind-caused impacts are to apply to the worst winds reaching the coast and the damage would be less elsewhere. Hurricane wind damage is also dependent upon such other factors as duration of high winds, change of wind direction, amount of accompanying rainfall, and age and strength of structures. Earlier versions of this scale - known as the Saffir-Simpson Hurricane Scale - incorporated central pressure and storm surge as components of the categories. The central pressure was utilized during the 1970s and 1980s as a proxy for the winds as accurate wind speed intensity measurements from aircraft reconnaissance were not routinely available for hurricanes until 1990. Storm surge was also quantified by category in the earliest published versions of the scale dating back to 1972. However, hurricane size (extent of hurricane force winds), local bathymetry (depth of near-shore waters), and topographic forcing can also be important in forecasting the actual coastal inundation, for which storm surge is only one contributing factor in near-shore deep-water locations such as Hawaii. Moreover, other aspects of hurricanes - such as the system's forward speed and angle to the coast - also impact the coastal inundation that is produced. Thus, to help reduce public confusion about the impacts associated with the various hurricane categories, as well as to provide a more scientifically defensible scale, the storm surge ranges, flooding impact and central pressure statements are being removed from the scale and only peak winds are employed in this revised version - the Saffir-Simpson Hurricane Wind Scale.
- Category One Hurricane:
Sustained winds 74-95 mph (64-82 kt or 119-153 km/hr). Damaging winds are expected. Some damage to building structures could occur, primarily to unanchored structures (such as school portables). Some damage is likely to poorly constructed signs. Loose outdoor items will become projectiles, causing additional damage. Persons struck by windborne debris risk injury and possible death. Numerous large branches of healthy trees will snap. Some trees will be uprooted, especially where the ground is saturated. Many areas will experience power outages with some downed power poles. Hurricane Iwa (passing just northwest of Kauai in 1982) and Hurricane Dot (landfall on Kauai in 1959) are examples of Category One hurricanes that directly impacted Hawaii.
- Category Two Hurricane:
Sustained winds 96-110 mph (83-95 kt or 154-177 km/hr). Very strong winds will produce widespread damage. Some roofing material, door, and window damage of buildings will occur. Considerable damage to unanchored structures and poorly constructed signs is likely. A number of glass windows in high rise buildings will be dislodged and become airborne. Loose outdoor items will become projectiles, causing additional damage. Persons struck by windborne debris risk injury and possible death. Numerous large branches will break. Many trees will be uprooted or snapped. Extensive damage to power lines and poles will likely result in widespread power outages that could last a few to several days. There is no record of a Category Two hurricane directly impacting Hawaii. Elsewhere in the United States, Hurricane Erin (1995, 100 mph at landfall in northwest Florida) and Hurricane Isabel (2003, 105 mph at landfall in North Carolina) are examples of Category Two hurricanes at landfall.
- Category Three Hurricane:
Sustained winds 111-129 mph (96-112 kt or 178-208 km/hr). Dangerous winds will cause extensive damage. Some structural damage to houses and buildings will occur with a minor amount of wall failures. Unanchored structures and poorly constructed signs are destroyed. Many windows in high rise buildings will be dislodged and become airborne. Persons struck by windborne debris risk injury and possible death. Many trees will be snapped or uprooted and block numerous roads. Near total power loss is expected with outages that could last from several days to weeks. There is no record of a Category Three hurricane directly impacting Hawaii. Elsewhere in the United States, Hurricane Rita (pdf) (2005, 115 mph landfall in east Texas/Louisiana) and Hurricane Jeanne (2004, 120 mph landfall in southeast Florida) are examples of Category Three hurricanes at landfall.
- Category Four Hurricane:
Sustained winds 130-156 mph (113-136 kt or 209-251 km/hr). Extremely dangerous winds causing devastating damage are expected. Some wall failures with some complete roof structure failures on houses will occur. All signs are blown down. Complete destruction of unanchored structures. Extensive damage to doors and windows is likely. Numerous windows in high rise buildings will be dislodged and become airborne. Windborne debris will cause extensive damage and persons struck by the wind-blown debris will be injured or killed. Most trees will be snapped or uprooted. Fallen trees could cut off residential areas for days to weeks. Electricity will be unavailable for weeks after the hurricane passes. Hurricane Iniki, which made landfall on Kauai in 1992, is an example of a Category Four hurricane at landfall in Hawaii.
- Category Five Hurricane:
Sustained winds greater than 157 mph (137 kt or 252 km/hr). Catastrophic damage is expected. Complete roof failure on many residences and industrial buildings will occur. Some complete building failures with small buildings blown over or away are likely. All signs blown down. Complete destruction of unanchored structures. Severe and extensive window and door damage will occur. Nearly all windows in high rise buildings will be dislodged and become airborne. Severe injury or death is likely for persons struck by wind-blown debris. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. There is no record of a Category Five hurricane directly impacting Hawaii. Elsewhere in the United States, Hurricane Camille (pdf) (1969, 190 mph at landfall in Mississippi) and Hurricane Andrew (1992, 165 mph at landfall in Southeast Florida) are examples of Category Five hurricanes at landfall.
More details about this experimental change can be found at http://www.weather.gov/infoservicechanges/sshws.pdf
Comments about the new Saffir-Simpson Hurricane Wind Scale? Please send us an email at W-HFO.Webmaster@noaa.gov