Tornadoes

Hurricanes 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.  However, they are also often found elsewhere embedded in the rainbands, well away from the center of the hurricane.

Some hurricanes 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.

We have no way at present to predict exactly which storms will spawn tornadoes or where they will touch down. The new Doppler radar systems have greatly improved the forecaster's warning capability, but the technology usually provides lead times from only a few minutes up to about 30 minutes. Consequently, preparedness is critical.

Tornado Facts

• When associated with hurricanes, tornadoes are not usually accompanied by hail or a lot of lightning, clues that citizens in other parts of the country watch for.

• Tornado production 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.

Fujita scale
The Fujita scale (F-scale) uses actual damage to determine a tornado’s wind speed

• F0 Gale Tornado
  40-72 mph
  Some damage to chimneys. Tree branches broken off. Shallow rooted trees uprooted.
• F1 Moderate Tornado
  73-112 mph
  Peels surface off roofs. Mobile homes overturned. Moving autos pushed off roads.
• F2 Significant Tornado
  113-157 mph
  Considerable damage. Roofs torn off frame houses. Large trees snapped or uprooted. Light-object missiles generated.
• F3 Severe Tornado
  158-206 mph
  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 mph
  Well-constructed houses leveled. Structures with weak foundations blown off some distance. Cars thrown and large missiles generated.
• F5 Incredible Tornado
  261-318 mph
  Strong frame houses lifted off foundations and disintegrated. Automobile-sized missiles fly through the air in excess of 100 mph. Trees debarked.

Related Information
• Tornado Safety Actions
• Historic Hurricanes

Related Multimedia
• Against the Wind (0.2mb)

Related Websites
• Storm Prediction Center

Additional Safety Information

Tornado Safety Actions - Homes

• Monitor NOAA Weather Radio.
• When a tornado watch is issued, be prepared to take action.
• When a tornado warning is issued, or a tornado is imminent, move to a small interior room away from windows.
• Consider constructing a tornado safe room in or adjacent to your home.

Tornado Safety Actions - Mobile and Manufactured Homes

• Monitor NOAA Weather Radio.
• Have a plan of where to go during a tornado threat—a nearby pre-identified safe structure within walking distance.
• When a tornado watch is issued, be prepared to take action.
• When conditions warrant, move to the pre-identified safe structure.
• If you live in a mobile or manufactured home park, get together with other residents and the park owner/manager to designate safe shelter areas in the park or community.

Tornado Safety Actions - Offices, Condominiums and Hotels

• Monitor NOAA Weather Radio.
• When action is required, take shelter in an interior hallway on a lower floor, closet or small room.
• As a last resort, get under heavy furniture, away from windows.