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Tropical Cyclone Hazards: Tornadoes

Tropical cyclones can also produce tornadoes that add to the storm's destructive power. Tornadoes are most likely to occur in the right-front quadrant of the hurricane relative to its motion. However, they are also often found elsewhere embedded in the rainbands, well away from the center of the tropical cyclones.

Some tropical cyclones seem to produce no tornadoes, while others develop multiple ones. Studies have shown that more than half of the landfalling hurricanes produce at least one tornado; Hurricane Buelah (1967) spawned 141 according to one study.

In general, tornadoes associated with hurricanes are less intense than those that occur in the Great Plains (see the Fujita Intensity Scale below). Nonetheless, the effects of tornadoes, added to the larger area of hurricane-force winds, can produce substantial damage.

  • When associated with hurricanes, tornadoes are not usually accompanied by hail or a lot of lightning.
  • Tornadoes can occur for days after landfall when the tropical cyclone remnants maintain an identifiable low pressure circulation.
  • They can also develop at any time of the day or night during landfall. However, by 12 hours after landfall, tornadoes tend to occur mainly during daytime hours.
A tornado watch is usually issued when a tropical cyclone is about to move onshore. The watch box is generally to the right of the tropical cyclones path.

Fujita Intensity Scale
The Fujita scale (F-scale) uses actual damage to determine a tornado's wind speed.
F-scale Name Wind (mph) Damage
F0 Gale Tornado 40-72 Some damage to chimneys. Tree branches broken off. Shallow rooted trees uprooted.
F1 Moderate Tornado 73-112 Peels surface off roofs. Mobile homes overturned. Moving autos pushed off roads.
F2 Significant Tornado 113-157 Considerable damage. Roofs torn off frame houses. Large trees snapped or uprooted. Light-object missiles generated.
F3 Severe Tornado 158-206 Severe damage. Roofs and some walls torn off well constructed homes. Trains overturned. Most trees in forests uprooted. Heavy cars lifted off ground.
F4 Devastating Tornado 207-260 Well-constructed houses leveled. Structures with weak foundations blown off some distance. Cars thrown and large missiles generated.
F5 Incredible Tornado 261-318 Strong frame houses lifted off foundations and disintegrated. Automobile-sized missiles fly through the air in excess of 100 mph. Trees debarked.


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