How do Tornados Form?

They are one of the most destructive forces in weather.  So how do funnel clouds and tornados form?

News 11 Chief Meteorologist Robert Shiels says it all starts when a massive storm called a "supercell" sweeps across the earth, sucking in massive amounts of warm air, and pushing out the cold. On the edges of this supercell, winds at different heights flow at different speeds, and that creates a horizontal spinning motion.

Then, updrafts of warm air push out these horizontal cycles, forming the typical funnel cloud shape that can reach down to the ground and become a tornado.

Tornadoes are classified into three types:

  • Weak Tornados (F0/F1) - These account for 70% of all tornadoes causing less than 5% of tornado deaths. They may last from one to ten minutes with winds speeds less than 113 mph.
  • Strong Tornados (F2/F3) - These account for 29% of all tornadoes causing nearly 30% of tornado deaths. They may last for over 20 minutes with wind speeds from 113 mph to 206 mph.
  • Violent Tornados (F4/F5) - These account for 1% of all tornadoes causing almost 70% of tornado deaths. They may last over one hour with wind speeds over 206 mph. The forward speed is usually around 30 mph, but can vary widely from stationary to nearly 70 mph.

Tornadoes generally move from the southwest to northeast, but they can be unpredictable and change directions anytime. The bottom line for safety is to all seek shelter during a tornado and never try to outrun one if your in a car. Tornadoes are often destructive and even deadly.

Knowing the difference between a tornado watch and a tornado warning can save your life.

  • Tornado Watch - Conditions are favorable for the development of thunderstorms that will have a strong capability of producing tornadoes.
  • Tornado Warning - A tornado has been spotted by a trained observer or Doppler radar has indicated a developing tornado and you should seek shelter immediately.

If a Tornado Warning is issued for you county here are some steps you can take.

  • If you are at home or in a small building move go to the basement. A basement provides the safest shelter from a tornado.
  • If there is not a basement in the building move to an interior room or hall. The room should be small, such as a bathroom or closet on the lowest level of you house.
  • If possible make sure there are no windows in the room to avoid injury from flying glass.
  • If you are at a school, hospital, factory, or shopping mall there should be a pre-designated shelter area.
  • If there is not, move to an interior hallway on the lowest floor avoiding large windows or glassed areas.
  • It is best if you stay away from large rooms like school gyms or dining rooms.
  • You should crouch down and protect your head with your hands.
  • If you are threatened by a tornado and you are in a high rise building move to center of the building.

History has proven the worst place to get caught in a tornado is a mobile home or car. If a tornado threatens, leave the mobile home or car and seek shelter in a sturdy shelter. If you are in a car and a sturdy shelter can't be reached, leave the car and lie in the nearest ditch, gully or low spot shielding your head with your hands. An automobile provides virtually no protection against the strong winds of a tornado.

There are many myths about tornadoes, but there are many things that have been proven true. Tornadoes do travel at about 30 mph, but can travel across land at speeds up to 70 mph. The typical tornado does move from the southwest to the northeast, but it is not uncommon for them to move erratically and travel in any direction. This is why it is so dangerous to try to outrun one in your car.

One of the biggest myths is whether to open your the windows in your home when a tornado is moving towards it. It was once thought opening them would prevent damage from a sudden drop in atmospheric pressure, but research shows pressure changes within a tornado are minor in comparison to the whole damage process. Opening windows may lead to more damage inside structures from the strong winds of a tornado. This means leave your windows closed when one threatens.

Here at News 11, our #1 mission is keeping you ahead of the storm.

Posted by AEB