25
RATING TORNADOES FACT
On April 3, 1974, 147 tornadoes touched down in the U.S.
Seven of those were rated EF5. No other EF5 tornadoes formed that year.
T
h
e
N
a
t
i
o
n
a
l
S
e
v
e
r
e
S
t
o
r
m
s
L
a
b
o
r
a
t
o
r
y
(
N
S
S
L
)
s
t
u
d
i
e
s
t
o
r
n
a
d
o
e
s
.
I
t
i
s
w
o
r
k
i
n
g
t
o
u
n
d
e
r
s
t
a
n
d
h
o
w
t
o
r
n
a
d
o
e
s
f
o
r
m
.
I
t
t
r
a
c
k
s
a
n
d
r
e
c
o
r
d
s
t
o
r
n
a
d
o
e
s
.
L
o
c
a
t
e
d
i
n
N
o
r
m
a
n
,
O
k
l
a
h
o
m
a
,
t
h
e
N
S
S
L
i
s
r
i
g
h
t
i
n
t
h
e
h
e
a
r
t
o
f
T
o
r
n
a
d
o
A
l
l
e
y
.
EF0
EF1
65–85 miles (105–137 km) per hour
86–110 miles (138–177 km) per hour
EF2
111–135 miles (178–217 km) per hour
EF3
136–165 miles (218–266 km) per hour
EF4
EF5
166–200 miles (267–322 km) per hour
greater than 200 miles (322 km) per hour
ENHANCED FUJITA SCALE
