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Subject: D1) How are Atlantic hurricanes ranked?
Contributed by Chris Landsea
The USA utilizes the Saffir-Simpson hurricane intensity scale (Simpson
and Riehl 1981) for the Atlantic and Northeast Pacific basins to give an
estimate of the potential flooding and damage to property given a
hurricane's estimated intensity:
Saffir-Simpson Scale
Saffir-Simpson Category |
Maximum sustained wind speed |
Minimum central pressure |
Storm surge |
mph | m/s |
kts |
mb |
ft |
m |
1 |
74-95 |
33-42 |
64-82 |
> 980 |
3-5 |
1.0-1.7 |
2 |
96-110 |
43-49 |
83-95 |
979-965 |
6-8 |
1.8-2.6 |
3 |
111-130 |
50-58 |
96-113 |
964-945 |
9-12 |
2.7-3.8 |
4 |
131-155 |
59-69 |
114-135 |
944-920 |
13-18 |
3.9-5.6 |
5 |
156+ |
70+ |
136+ |
< 920 |
19+ |
5.7+ |
Note : Classification by central pressure was ended
in the 1990s, and wind speed alone is now used. These estimates of the
central pressure that accompany each category are for reference only.
Note : These surge values are for reference only. The actual storm
surge experienced will depend on offshore bathymetery and onshore
terrain and construction.
Damage
Category | Level | Description | Example |
1 |
MINIMAL |
Damage primarily to shrubbery, trees, foliage, and unanchored
homes. 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. |
Hurricane Earl (1998) |
2 |
MODERATE |
Considerable damage to shrubbery and tree foliage; some
trees blown down. Major damage to exposed mobile homes. Extensive
damage to poorly constructed signs. Some damage to roofing materials
of buildings; some window and door damage. No major damage to
buildings. Coast roads and low-lying escape routes inland cut by
rising water 2 to 4 hours before arrival of hurricane center.
Considerable damage to piers. Marinas flooded. Small craft in
unprotected anchorages torn from moorings. Evacuation of some
shoreline residences and low-lying areas required. |
Hurricane Georges (1998) |
3 |
EXTENSIVE |
Foliage torn from trees; large trees blown down.
Practically all poorly constructed signs blown down. Some damage to
roofing materials of buildings; some wind and door damage. Some
structural damage to small buildings. Mobile homes destroyed. Serious
flooding at coast and many smaller structures near coast destroyed;
larger structures near coast damaged by battering waves and floating
debris. Low-lying escape routes inland cut by rising water 3 to 5
hours before hurricane center arrives. Flat terrain 5 feet of less
above sea level flooded inland 8 miles or more. Evacuation of low-
lying residences within several blocks of shoreline possibly required. |
Hurricane Fran (1996) |
4 |
EXTREME |
Shrubs and trees blown down; all signs down. Extensive
damage to roofing materials, windows and doors. Complete failures of
roofs on many small residences. Complete destruction of mobile homes.
Flat terrain 10 feet of less above sea level flooded inland as far as
6 miles. Major damage to lower floors of structures near shore due to
flooding and battering by waves and floating debris. Low-lying escape
routes inland cut by rising water 3 to 5 hours before hurricane center
arrives. Major erosion of beaches. Massive evacuation of all
residences within 500 yards of shore possibly required, and of single-
story residences within 2 miles of shore. |
Hurricane Betsy (1965) |
5 |
CATASTROPHIC |
Shrubs and trees blown down; considerable damage to
roofs of buildings; all signs down. Very severe and extensive damage
to windows and doors. Complete failure of roofs on many residences and
industrial buildings. Extensive shattering of glass in windows and
doors. Some complete building failures. Small buildings overturned or
blown away. Complete destruction of mobile homes. Major damage to
lower floors of all structures less than 15 feet above sea level within
500 yards of shore. Low-lying escape routes inland cut by rising water
3 to 5 hours before hurricane center arrives. Massive evacuation of
residential areas on low ground within 5 to 10 miles of shore possibly
required. |
Hurricane Camille (1969) |
Note that tropical storms are not on this scale, but can
produce extensive damage with rainfall-produced flooding. Note
also that category 3, 4, and 5 hurricanes are collectively
referred to as major (or intense) hurricanes. These major
hurricanes cause over 83% of the damage in the USA even though
they account for only 21% of tropical cyclone landfalls
(Landsea 1993).
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