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by National
Weather Service, National Hurricane Center, Tropical Prediction Center
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 and the shape of the coastline, in the landfall region.
Note that all winds are using the U.S. 1-minute average.
- Category One Hurricane:
- Winds 74-95 mph (64-82 kt or 119-153 km/hr). 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.
Hurricane Lili of
2002 made landfall on the Louisiana coast as a Category One hurricane.
Hurricane Gaston
of 2004 was a Category One hurricane that made landfall along the
central South Carolina coast.
-
- Category Two Hurricane:
- Winds 96-110 mph (83-95 kt or 154-177 km/hr). 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 Frances
of 2004 made landfall over the southern end of Hutchinson Island,
Florida as a Category Two hurricane.
Hurricane Isabel
of 2003 made landfall near Drum Inlet on the Outer Banks of North
Carolina as a Category 2 hurricane.
-
- Category Three Hurricane:
- Winds 111-130 mph (96-113 kt or 178-209 km/hr). 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
Jeanne and Ivan
of 2004 were Category Three hurricanes when they made landfall in
Florida and in Alabama, respectively.
-
- Category Four Hurricane:
- Winds 131-155 mph (114-135 kt or 210-249 km/hr).
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
Charley of 2004 was a Category Four hurricane made landfall in
Charlotte County, Florida with winds of 150 mph.
Hurricane Dennis
of 2005 struck the island of Cuba as a Category Four hurricane.
-
- Category Five Hurricane:
- Winds greater than 155 mph (135 kt or 249 km/hr).
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. Only 3 Category Five
Hurricanes have made landfall in the United States since records began:
The Labor Day Hurricane of 1935, Hurricane Camille (1969), and
Hurricane Andrew
in August, 1992. The 1935 Labor Day Hurricane struck the Florida Keys
with a minimum pressure of 892 mb--the lowest pressure ever observed in
the United States. Hurricane Camille struck the Mississippi Gulf Coast
causing a 25-foot storm surge, which inundated Pass Christian.
Hurricane Andrew
of 1992 made landfall over southern Miami-Dade County, Florida causing
26.5 billion dollars in losses--the costliest hurricane on record. In
addition, Hurricane
Gilbert of 1988 was a Category Five hurricane at peak intensity and
is the strongest Atlantic tropical cyclone on record with a minimum
pressure of 888 mb.
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