Tornadoes topic of day four for Severe Weather Awareness week

DULUTH, MN– We are slowly coming to an end to Severe Weather Awareness week and Thursday’s topic is on tornadoes.

As mentioned in Monday’s topic of watches and warnings, it is always important to know what the difference between the two.

A watch means conditions are favorable for severe thunderstorm to develop and you will want to be aware of the changing weather conditions and plan accordingly.

A warning means that severe weather is occurring and those who are in the path need to act quickly and seek shelter.

In 1971, Dr. Tetsuya Fujita created the tornado scale, named the Fujita Scale (F-Scale). His goal in developing the F-Scale was to categorize each tornado by intensity and area and then estimate the wind speed associated from the damaged caused.

The Fujita Scale was tweaked and changed in 2007, and is now known as the Enhanched Fujita Scale. The scale was redesigned to better show damage surveys from tornadoes and how structures are designed. The new scale is shown below:

More than 75% of tornadoes that develop are usually on the lower end of the scale (EF0-EF1), but there are some tornadoes that can reach the top of the scale. Less than one percent of tornadoes reach the EF4-EF5 level.

The average size of a tornado is fairly small, usually a few hundred feet wide and usually travels a few miles on average lasting only a few minutes, however some tornadoes can grow to a mile wide or larger, can travel for more than 20, 30 miles and can last 30 minutes or longer.

Tornadoes can also appear in many shapes and sizes. The most common shapes a tornado can be include a rope, cone or wedge.

More than 1,000 tornadoes hit the U.S. each year on average, with April through June being the peak of tornado season.

  • Here are some records on tornadoes:
  • Fastest winds observed: 302 mph on May 3, 1999 in Bridge Creek, OK
  • Largest tornado outbreak: 360 tornadoes from April 25-28, 2011 across the Southern, Midwestern and Northeastern parts of the U.S. (known as the Super Outbreak)
  • Most tornadoes in one day: 216 tornadoes on April 27, 2011 during the Super Outbreak
  • Widest tornado: 2.6 miles wide, May 31, 2013 in El Reno, OK
  • Costliest tornado: $2.8 billion, May 22, 2011 in Joplin, MO

It is always important to know where to go if a tornado warning is issued. Here are some safety tips to keep in mind, according to the Homeland Security and Emergency Management (HSEM):

  • If you are in a mobile home, evacuate immediately
  • If you are in your vehicle, get out and seek shelter inside a sturdy structure or if no structure is near, lie flat in a ditch or low ground and be sure to cover your head from flying debris. Also try to stay away from trees and vehicles, as they can act as flying debris
  • Never seek shelter underneath an overpass, since it acts like a wind tunnel
  • The best place to seek shelter is inside a basement or underground shelter
  • If neither of those options are available, you want to seek shelter inside a small interior room, such as a bathroom or closet, and be as close to the center of the house as possible, as you want to put as many walls between you and the outside.
  • Always avoid rooms with windows when seeking shelter

Friday is the last day of Severe Weather Awareness week and the last topic is on extreme heat.

The mock tornado watches and warnings for Wisconsin have been postponed until Friday, April 12th, and Minnesota has cancelled its tornado drill for the season.

Officials say the mock watch and warnings will be held at the same times as originally scheduled – 1:45 p.m. and 6:45 p.m.

RELATED: Tips on Flooding highlight day three of Severe Weather Awareness Week

Austin Haskins

Austin Haskins

Meteorologist/Web Producer

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