WeAther-relAteD scAles
saffir-simpson hurricane scale
•
Tropical Storm
Winds 39–73 mph
•
Category 1 Hurricane — winds 74–95 mph (64–82
knots); pressure greater than 980 mbar; storm surge 3–5 ft
(1 .0–1 .7 m)
No real damage to buildings . Damage to unanchored mo-
bile homes . Some damage to poorly constructed signs .
Also, some coastal flooding and minor pier damage .
— Examples: Irene 1999 and Allison 1995
•
Category 2 Hurricane — winds 96–110 mph (83–95 knots);
pressure 979–965 mbar; storm surge 6–8 ft (1 .8–2 .6 m)
Some damage to building roofs, doors and windows .
Considerable damage to mobile homes . Flooding dam-
ages piers and small craft in unprotected moorings
may break their moorings . Some trees blown down .
— Examples: Bonnie 1998, Georges (FL & LA) 1998 and
Gloria 1985
•
Category 3 Hurricane — winds 111–130 mph (96–113
knots); pressure 964–945 mbar; storm surge 9–12 ft (2 .7–
3 .8 m)
Some structural damage to small residences and utility build-
ings . Large trees blown down . Mobile homes and poorly
built signs destroyed . Flooding near the coast destroys
smaller structures with larger structures damaged by
floating debris . Terrain may be flooded well inland .
— Examples: Keith 2000, Fran 1996, Opal 1995, Alicia
1983 and Betsy 1965
•
Category 4 Hurricane — winds 131–155 mph (114–135
knots); pressure 944–920 mbar; storm surge 13–18 ft (3 .9–
5 .6 m)
More extensive curtainwall failures with some complete roof
structure failure on small residences . Major erosion of
beach areas . Terrain may be flooded well inland .
— Examples: Hugo 1989 and Donna 1960
•
Category 5 Hurricane — winds 156 mph and up (135+
knots); pressure less than 920 mbar; storm surge 19+ ft
(5 .7+ m)
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 .
— Examples: Andrew (FL) 1992, Camille 1969 and Labor
Day 1935
fujita tornado Damage scale
The original Fujita Scale was modified by NOAA in February
2007 and is now called the Enhanced Fujita Scale (EF) . It is an
operational scale based on the estimated speed of three-second
wind gusts, as indicated by typical damage levels . The table below
describes the damage levels according to the original scale . In the
enhanced scale, the damage is measured by a more elaborate set of
criteria (see http://www .spc .noaa .gov/efscale/ef-scale .html) .
beaufort Wind scale
The Beaufort Wind Scale was devised by British Rear-Admiral Sir Francis Beaufort in 1805 based on observations of the effects of the
wind .
EF
Number
3 s Gusts
(mph)
Typical damage (according to the original Fujita Scale)
0
65–85
Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign
boards damaged .
1
86–110 Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving
autos blown off roads .
2
111–135 Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large
trees snapped or uprooted; light-object missiles generated; cars lifted off ground .
3
136–165 Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in
forest uprooted; heavy cars lifted off the ground and thrown .
4
166–200 Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some
distance; cars thrown and large missiles generated .
5
Over 200 Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles
fly through the air in excess of 100 meters (109 yd); trees debarked; incredible phenomena will occur .
Force
Wind
(knots)
WMO
classification
Appearance of wind effects
On the water
On land
0
< 1
Calm
Sea surface smooth and mirror-like
Calm, smoke rises vertically
1
1–3
Light Air
Scaly ripples, no foam crests
Smoke drift indicates wind direction, still wind vanes
2
4–6
Light Breeze
Small wavelets, crests glassy, no breaking
Wind felt on face, leaves rustle, vanes begin to move
3
7–10 Gentle Breeze
Large wavelets, crests begin to break, scattered
whitecaps
Leaves and small twigs constantly moving, light flags
extended
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