Geoscience Reference
In-Depth Information
Table 7.3 TORRO scale parameters
FI
v, m/s
Tornado description
Intensity
description
Damage description
FC
Funnel cloud aloft (not
a tornado)
Weak
No damage to structures, unless on tops of tallest
towers, or to radiosondes, balloons, and aircraft. No
damage in the country, except possibly agitation to
highest tree-tops and effect on birds and smoke. Record
FC when not known to have reached ground level. A
whistling or rushing sound aloft may be noticed
F0
17
-
24
Light
•
Loose light litter raised from ground level in spirals
•
Tents, marquees, awnings seriously disturbed
•
Some exposed tiles, slates on roofs dislodged. Twigs
snapped; trail visible through crops
•
Wheelie bins tipped and rolled
•
Garden furniture and pots disturbed
•
Deck chairs, small plants, heavy litter becomes
airborne
•
Minor damage to sheds
•
More serious dislodging of tiles, slates
•
Chimney pots dislodged. Wooden fences flattened
•
F1
25
-
32
Mild
Slight damage to hedges and trees
•
Some windows already ajar blown open breaking
latches
F2
33
-
41
Moderate
•
Heavy mobile homes displaced. Light caravans blown
over
•
Garden sheds destroyed. Garage roofs torn away and
doors imploded
•
Much damage to tiled roofs and chimneys. Ridge tiles
missing
•
General damage to trees, some big branches twisted or
snapped off, small trees uprooted
•
Bonnets blown open on cars
•
Weak or old brick walls toppled
•
Windows blown open or glazing sucked out of frames
F3
42
-
51
Strong
•
Mobile homes overturned/badly damaged. Light
caravans destroyed. Garages and weak outbuildings
destroyed
•
House roof timbers considerably exposed. Some of the
bigger trees snapped or uprooted
•
Some heavier debris becomes airborne causing
secondary damage breaking windows and impaling
softer objects
•
Debris carried considerable distances. Garden walls
blown over
•
Eyewitness reports of buildings physically shaking
•
Mud sprayed up the side of buildings
•
Motorcars levitated. Mobile homes airborne/destroyed
•
Sheds airborne for considerable distances. Entire roofs
removed from some houses
•
Roof timbers of stronger brick or stone houses
completely exposed. Gable ends torn away
•
F4
52
-
61
Severe
Strong
Numerous trees uprooted or snapped. Traf
c Signs
folded or twisted
(continued)
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