Tornado Information


Each year in the United States there are an average of 1,200 tornadoes that cause 70 fatalities and 1,500 injuries. The average number of tornadoes in Tennessee has doubled over the past 7 years. The peak months for tornadoes in Tennessee are March through May, but tornadoes can occur at anytime of the year.

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 can 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, while peak months in the northern states are during the late spring and summer.
• Tornadoes are most likely to occur between 3 and 9 p.m. but can happen at any time.

Weak Tornadoes

• 88% of all tornadoes
• Less than 5% of tornado deaths
• Lifetime 1 - 10+ minutes
• Winds less than 110 mph
 

Strong Tornadoes

• 11% of all tornadoes
• Nearly 30% of all tornado deaths
• May last 20 minutes or longer
• Winds 110-205 mph
 

Violent Tornadoes

• Less than 1% of all tornadoes
• 70% of all tornado deaths
• Lifetime can exceed 1 hour
• Winds greater than 205 mph
 

Be Prepared

• When a tornado is coming, you only have a short amount of time to make life or death decisions. Advance planning and quick responses are the keys to surviving a tornado.
• Mobile Homes are particularly vulnerable to strong winds. A mobile home can overturn very easily even if precautions have been taken to tie it down. When a tornado warning is issued, take shelter in a building with a strong foundation. If shelter is not available, then lie in a ditch or low-lying area far away from the mobile home.

If a tornado watch is issued

• Remain alert for approaching storms. This is the time to remind everyone where the safest places are.
• Listen to NOAA weather radio for further developments.
 
 

If a tornado warning is issued

• If in a mobile home, get out and find shelter elsewhere.
• Stay away from windows.
• Go to a windowless interior room, storm cellar, basement or lowest level of the building.
• If there is no basement, go to an inner hallway or a smaller inner room with no windows, such as a closet or bathroom.
• Go to the center of the room. Stay away from corners, they tend to attract debris.
• Get under a sturdy workbench, heavy table or desk or sturdy furniture and hold on to it.
• Use arms to protect head and neck.

Tornado Myths and Facts

Myth: Areas near lakes, rivers, and mountains are safe from tornadoes.
Fact: No place is safe from tornadoes. A tornado near Yellowstone National Park left a path of destruction up and down a 10,000 foot mountain.

Myth: The low pressure with a tornado causes buildings to "explode" as the tornado passes overhead.
Fact: Violent winds and debris slamming into buildings cause most structural damage.

Myth: Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
Fact: Leave the windows alone. The most important action is to immediately go to a safe shelter.

Myth: If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm.
Fact: The best thing to do is to seek the best available shelter. Many people are injured or killed when remaining in their vehicles.

Myth: People caught in the open should seek shelter under highway overpasses.
Fact: Take shelter in a sturdy reinforced building if at all possible. Overpasses, ditches, and culverts may provide limited protection from a tornado, but your risk will be greatly reduced by moving inside a strong building.

Tornado information courtesy of the National Weather Service.