Saffir-Simpson Hurricane Scale

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Saffir-Simpson Hurricane Scale
Category	Wind speed	Storm surge
	mph (km/h)	ft (m)
5	≥156 (≥250)	>18 (>5.5)
4	131–155 (210–249)	13–18 (4.0–5.5)
3	111–130 (178–209)	9–12 (2.7–3.7)
2	96–110 (154–177)	6–8 (1.8–2.4)
1	74–95 (119–153)	4–5 (1.2–1.5)
Additional classifications
Tropical storm	39–73 (63–117)	0–3 (0–0.9)
Tropical depression	0–38 (0–62)	0 (0)

The Saffir-Simpson Hurricane Scale is a scale classifying most Western Hemisphere tropical cyclones that exceed the intensities of "tropical depressions" and "tropical storms", and thereby become hurricanes. The categories into which the scale divides hurricanes are distinguished by the intensities of their respective sustained winds. The classifications are intended primarily for use in measuring the potential damage and flooding a hurricane will cause upon landfall. The Saffir-Simpson Hurricane Scale is used only to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas label their tropical cyclones as "cyclones" and "typhoons", and use their own classification scales.

1 History
2 Categories
3 Category 6
4 See also
5 References
6 External links

[edit] History

The scale was developed in 1969 by civil engineer Herbert Saffir and Bob Simpson, at that time the director of the U.S. National Hurricane Center.^[1]

The initial scale was developed by Saffir while on commission from the United Nations to study low-cost housing in hurricane-prone areas. While performing the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. Knowing the utility of the Richter magnitude scale in describing earthquakes, he devised a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the NHC, and Simpson added in the effects of storm surge and flooding. The scale does not take into account rainfall or location, which means a Category 2 hurricane that hits a major city will likely do far more damage than a Category 5 hurricane that hits a rural area.^[2]

[edit] Categories

The five categories are, in order of increasing intensity:

Category	Sustained winds	33–42 m/s	74–95 mph	64–82 kt	119–153 km/h
	Storm surge	4–5 ft		1.2–1.5 m
	Central pressure	28.94 inHg		980 mbar
	Potential damage	No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal flooding and minor pier damage.^[5]
	Example storms	Bess (1974) – Jerry (1989) – Ismael (1995) – Danny (1997) – Gaston (2004)
Category	Sustained winds	43–49 m/s	96–110 mph	83–95 kt	154–177 km/h
	Storm surge	6–8 ft		1.8–2.4 m
	Central Pressure	28.50–28.91 inHg		965–979 mbar
	Potential damage	Some roofing material, door, and window damage. Considerable damage to vegetation, mobile homes, etc. Flooding damages piers and small craft in unprotected anchorages may break their moorings.^[5]
	Example storms	Carol (1954) – Diana (1990) – Erin (1995) – Marty (2003) – Juan (2003)
Category	Sustained winds	50–58 m/s	111–130 mph	96–113 kt	178–209 km/h
	Storm surge	9–12 ft		2.7–3.7 m
	Central pressure	27.91–28.47 inHg		945–964 mbar
	Potential damage	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 may be flooded well inland.^[5]
	Example storms	Alma (1966) – Alicia (1983) – Roxanne (1995) – Fran (1996) – Isidore (2002)
Category	Sustained winds	59–69 m/s	131–155 mph	114–135 kt	210–249 km/h
	Storm surge	13–18 ft		4.0–5.5 m
	Central pressure	27.17–27.88 inHg		920–944 mbar
	Potential damage	More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach areas. Terrain may be flooded well inland.^[5]
	Example storms	"Galveston" (1900) – Hazel (1954) – Iniki (1992) – Iris (2001) – Charley (2004)
Category	Sustained winds	≥70 m/s	≥156 mph	≥136 kt	≥250 km/h
	Storm surge	≥19 ft		≥5.5 m
	Central pressure	<27.17 inHg		<920 mbar
	Potential damage	Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.^[5]
	Example storms	"Labor Day" (1935) – "Mexico" (1959) – Camille (1969) – Gilbert (1988) – Andrew (1992)

The U.S. National Hurricane Center classifies hurricanes of Category 3 and above as major hurricanes. The definition of sustained winds recommended by the World Meteorological Organization (WMO) and used by most weather agencies is that of a 10-minute average at a height of 10 m (33 ft) . The U.S. weather service defines sustained winds based on 1-minute average speed, also measured 10 m (33 ft) above the surface..^[3]^[4] Central pressure values are approximate. Intensity of example hurricanes is from both the time of landfall and the maximum intensity.^[5]

[edit] Category 6

There is no such category on this scale, and any mention of a Category 6 tropical cyclone is fictitious or incorrect.

According to Robert Simpson, there is no reason for a Category 6 on the Saffir-Simpson Scale because it is designed to measure the potential damage of a hurricane to man-made structures.^[6] If the speed of the hurricane is above 156 mph, then the damage to a building will be "serious no matter how well it's engineered". However, the result of new technologies in construction leads some to suggest that an increase in the number of categories is necessary. This suggestion was emphasized after the devastating effects of the 2005 Atlantic hurricane season. During that year Hurricane Emily, Hurricane Katrina, Hurricane Rita, and Hurricane Wilma all became Category 5 hurricanes. A few newspaper opinionists and scientists have brought up the suggestion of introducing Category 6 since then.^[7]

[edit] See also

Tropical cyclones Portal

Beaufort scale - For winds less intense than hurricane strength.
Fujita scale - For tornado intensity with damage correlated to wind speeds. The system was also intended for applicability in hurricanes and indeed is utilized by engineers in hurricane damage assessment.
Severe weather terminology