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The
Saffir-Simpson Hurricane Scale
The Saffir-Simpson
Hurricane Scale is a 1-5 rating based on the 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. Note that all
winds are using the U.S. 1-minute average.
- Category One
Hurricane (Winds
74-95 mph):
- Storm surge
generally 4-5 ft above normal. 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.
Hurricanes Allison
of 1995 and Danny
of 1997 were Category One hurricanes at peak intensity.
- Category Two
Hurricane (Winds
96-110 mph):
- Storm surge
generally 6-8 feet above normal. 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 center. Small craft in unprotected
anchorages break moorings. Hurricane
Bonnie of 1998 was a Category Two hurricane when it hit
the North Carolina coast, while Hurricane
Georges of 1998 was a Category Two Hurricane when it hit
the Florida Keys and the Mississippi Gulf Coast.
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- Category Three
Hurricane (Winds
111-130 mph):
- Storm surge
generally 9-12 ft above normal. 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 center of the hurricane. Flooding near the coast
destroys smaller structures with larger structures damaged by
battering from floating debris. Terrain continuously lower
than 5 ft above mean sea level may be flooded inland 8 miles
(13 km) or more. Evacuation of low-lying residences with
several blocks of the shoreline may be required. Hurricanes Roxanne
of 1995 and Fran
of 1996 were Category Three hurricanes at landfall on the
Yucatan Peninsula of Mexico and in North Carolina,
respectively.
- Category Four
Hurricane (Winds
131-155 mph):
- Storm surge
generally 13-18 ft above normal. 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 center of the
hurricane. Major damage to lower floors of structures near the
shore. Terrain lower than 10 ft above sea level may be flooded
requiring massive evacuation of residential areas as far
inland as 6 miles (10 km). Hurricane
Luis of 1995 was a Category Four hurricane while moving
over the Leeward Islands. Hurricanes Felix
and Opal
of 1995 also reached Category Four status at peak intensity.
- Category Five
Hurricane (Winds
greater than 155 mph ):
- Storm surge
generally greater than 18 ft above normal. 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 center of the
hurricane. Major damage to lower floors of all structures
located less than 15 ft above sea level and within 500 yards
of the shoreline. Massive evacuation of residential areas on
low ground within 5-10 miles (8-16 km) of the shoreline may be
required. Hurricane
Mitch of 1998 was a Category Five hurricane at peak
intensity over the western Caribbean. Hurricane
Gilbert of 1988 was a Category Five hurricane at peak
intensity and is one of the strongest Atlantic tropical
cyclones of record.
Source:
NOAA
Hurricane
Watch
The onset of
hurricane conditions is possible within 36 hours
Hurricane Warning
The onset of hurricane conditions is likely within 24 hours.
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