Tornado Strength - Fujita Scale

The Enhanced Fujita (EF) Scale was devised by a panel of meteorologists and engineers convened by the Wind Science and Engineering Research Center at Texas Tech University. The Weather Channel's severe weather expert Dr. Greg Forbes was on the team of experts who determined the revised wind speed ranges.

The original Fujita Scale was devised in 1971 by "Mr. Tornado," Dr. Ted Fujita, of The University of Chicago. It gave ratings of F0 to F5 based upon the type and severity of damage the tornado produced. At that time there were very few actual measurements of tornado wind speeds that he could relate to the damage, but he used them -- together with a lot of insight -- to devise approximate wind speed ranges for each damage category.

The Fujita scale classifies tornadoes according to the damage they cause. Almost half of all tornadoes fall into the F1 or "moderate damage" category. These tornadoes reach speeds of 73-112 mph and can overturn automobiles and mobile homes, rip off the roofs of houses, and uproot trees. Only about one percent of tornadoes are classified as F5, causing "incredible damage". With wind speeds in excess of 261 mph, these tornadoes are capable of lifting houses off their foundations and hurling them considerable distances.

Tornado Scales and Damage Charts - Click to Enlarge

Here are some fun tornado facts.

• The most powerful Tornadoes occur in the United States.
• A typical tornado only lasts for a few minutes.
• Every tornado has its own color, sound and shape.
• The fastest tornadoes travel over 70 miles per hour.
• The chances that a tornado is a F5, the highest classification for a tornado on the F-scale, is less than 0.1%
• Tornadoes have been reported in every state in the US and also in every season.
• A Tornado can occur at any time, but most often between 3pm and 9pm.

Here are some of the things that people describe

when they tell about a tornado experience:

• A sickly greenish or greenish black color to the sky.
• If there is a watch or warning posted, then the fall of hail should be considered as a real danger sign. Hail can be common in some areas, however, and usually has no tornadic activity along with it.
• A strange quiet that occurs within or shortly after the thunderstorm.
• Clouds moving by very fast, especially in a rotating pattern or converging toward one area of the sky.
• A sound a little like a waterfall or rushing air at first, but turning into a roar as it comes closer. The sound of a tornado has been likened to that of both railroad trains and jets.
• Debris dropping from the sky. An obvious "funnel-shaped" cloud that is rotating, or debris such as branches or leaves being pulled upwards, even if no funnel cloud is visible.