Tornadoes
Tornado Facts
- A tornado is a violently rotating column of air extending from a thunderstorm to the ground.
- Tornadoes may appear nearly transparent until dust and debris are picked up or a cloud forms within the funnel.
- The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction.
- The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.
- The strongest tornadoes have rotating winds of more than 250 mph.
- Tornadoes can accompany tropical storms and hurricanes as they move onto land.
- Waterspouts are tornadoes which form over warm water. They can move onshore and cause damage to coastal areas.
When and Where Tornadoes Occur
- Tornadoes can occur at any time of the year.
- Tornadoes have occurred in every state, but they are most frequent east of the Rocky Mountains during the spring and summer months.
- In the southern states, peak tornado occurrence is March through May.
- Tornadoes are most likely to occur between 3 and 9 p.m. but can happen at any time.
Tornado Safety Rules
- In a home or other building, move to a predesignated shelter, such as a basement.
- If an underground shelter is not available, move to a small interior room or hallway on the lowest floor. Put as many walls as possible between you and the outside.
- Stay away from windows.
- Do not try to outrun a tornado in your car; instead, leave it immediately for safe shelter.
- If caught outside or in a vehicle, lie flat in a nearby ditch or depression and cover your head with your hands.
- Be aware of flying debris. Flying debris from tornadoes causes most fatalities and injuries.
- Mobile homes, even if tied down, offer little protection from tornadoes. You should leave a mobile home and go to the lowest floor of a sturdy nearby building or a storm shelter.
Enhance Fujita Tornado Damage Scale
EF0: Light Damage (65-85 mph)
Peels surface off some roofs; some damage to gutters or siding; branches broken off trees; shallow rooted trees pushed over.
EF1: Moderate Damage (86-110 mph)
Roofs severely stripped; mobile homes overturned or badly damaged; loss of exterior doors; windows and other glass broken.
EF2: Considerable Damage (111-135 mph)
Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
EF3: Severe Damage (136-165 mph)
Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations blown away some distance.
EF4: Devastating Damage (166-200 mph)
Well-constructed houses and whole frame houses completely leveled; cars thrown and small missiles generated.
EF5: Incredible Damage (>200 mph)
Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 m (109 yd); high-rise buildings have significant structural deformation; incredible phenomena will occur. So far only one EF5 tornado has been recorded since the Enhanced Fujita Scale was introduced on February 1, 2007.