| Subject: D1) How
are Atlantic hurricanes ranked?
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
Category |
Maximum sustained
1 minute wind speed |
Minimum surface 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+ |
Damage Description
| Cat |
Descriptor |
Recent Example |
| 1 |
MINIMAL |
Hurricane Gaston
(2004) |
| 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. |
| 2 |
MODERATE |
Hurricane
Frances (2004) |
| 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. |
| 3 |
EXTENSIVE |
Hurricane Ivan (2004) |
| 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 or less above sea level flooded inland 8 miles or
more. Evacuation of low- lying residences within several
blocks of shoreline possibly required. |
|
4 |
EXTREME |
Hurricane Charley (2004)
|
| 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 or 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. |
|
5 |
CATASTROPHIC |
Hurricane Andrew (1992) |
| 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. |
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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