The Retired Fujita Tornado Scale: Why was it a Flawed Science?

From 1971 to 2007, meteorologists used the Fujita scale, invented by Tetsuya Fujita, to measure the intensity of tornadoes. It was broken down from 0 to 6 according to the damage a tornado causes. This was then used to guesstimate the wind speed of the funnel. In this article, we'll go through each of the tornado levels on the Fujita scale and the type of damage each can cause, plus you'll learn why the scale, which has now been updated, was a flawed tool to measure the strength of tornadoes.

An F0 tornado on the Fujita scale had wind speeds between 40 and 72 miles per hour (mph). It causes only light damage to structures like chimneys, tree branches, and may knock over trees that are shallowly planted.

An F1 tornado on the Fujita scale had wind speeds between 73 and 112 mph. With this type of storm, you may see the surface of a roof peeled off, mobile homes overturned or pushed off their foundation, moving cars pushed off their course. This range on the scale is also the lowest level of hurricane wind speed.

An F2 tornado on the Fujita scale had wind speeds between 113 and 157 mph. This tornado causes significant damage, such as: torn off roofs, demolished mobile homes, uprooted or snapped larger trees, and light objects turned into airborne missiles.

An F3 tornado on the Fujita scale had wind speeds between 158 and 206 mph. Expect to see severe damage like walls and roofs torn off of houses, most trees uprooted, heavy cars lifted and thrown off the ground, and trains overturned.

An F4 tornado on the Fujita scale had wind speeds between 207 and 260 mph. This type of tornado will level well-built houses, blow weak structures significant distances away from their foundation, and throw cars and other large objects as missiles.

An F5 tornado on the Fujita scale had wind speeds between 261 and 318 mph. You'll see strongly built houses carried considerable distances away from their foundations or disintegrating, car-sized missiles being thrown for yards, and trees being debarked and asphalt being ripped off the road.

The inconceivable F6 tornado on the Fujita scale would have had wind speeds of 319 all the way to the level of sound (700 miles per hour). As far as we know, there's never been an identifiable F6 tornado, though there have been false claims of F5 tornadoes possibly reaching that level. Even if there were an F6 storm, the likelihood of being able to prove that with modern-day technology would have been slim.

Since the Fujita scale only measured the damage caused by tornadoes and not actual wind measurements, using it to categorize tornadoes wasn't an exact science. Tornado damage does depends on other factors, such as: structure of buildings hit, the shape of objects hit, the wind direction at which things are hit, and where the tornado hits.

For example, you could have a pretty strong tornado that touches down in an open area where there's nothing to damage, but it might have been classified as a F1 or F2 due to the lack of visible damage. Plus, a structure that's well-built can more easily withstand higher winds (and therefore be thought to have lesser wind speed than it actually does) while a poorly built structure might get destroyed even in weaker winds (and therefore the tornado may have gotten a higher ranking on the Fujita scale than it deserved).

The old Fujita scale was replaced in early 2007 with the enhanced F-scale, which does take other factors into consideration to better estimate the wind speed of a tornado but is still pretty much an instrument that depends on storm damage. Now you have a better understanding about the different tornado rankings and what affects those rankings.