New Tornado Scale

By: Sarah Goebel Email
By: Sarah Goebel Email

Just in time for tornado season, The National Weather Service has updated the scale used to determine a tornado's intensity.

The Fujita Scale, also known as the F Scale, was introduced in the 1970's after several devastating tornadoes ripped through parts of the U.S., but new studies show the F Scale isn't as accurate as originally thought.

"Judging by the amount of damage they found they could then assign a scale to it ranging from F-0 to F-5 with F-0 being a little bit of damage to F-5 being a lot of damage," said Dr. Greg Goodrich, a Geography and Geology Professor at Western Kentucky University, but the original F Scale wasn't completely accurate.

Scientists were making educated estimates on a tornado's wind speed and there was no concrete scientific proof to their grading.

"The structural engineers said how do you know it was 300 mile per hour winds when a house hit by 100 mile an hour winds is completely destroyed," Dr. Goodrich said.

There is no way for scientists to know the wind speed of a tornado until after it has passed.

So for the past six years scientists have been working with structural engineers to come up with a better scale when determining a tornado's ranking.

"Now they have 28 different damage indicators," Dr. Goodrich said.

This new scale is called the Enhanced Fujita Scale, or the EF Scale. It's based on the original scale, but scientists say it's more accurate because engineers know the wind speeds different structures can handle.

"The main difference between the F Scale and EF Scale is that they now have more damage assessments so the have different types of structures that they're able to then compare okay what kind of damage occurred to things such as a barn, a house, a shopping center, or a forest," Dr. Goodrich said.

Not only will the new scale measure wind damage it will also become a more effective way to track storms.

"For scientists that study climate change and are trying to determine if storms are getting worse now they have a better understanding," Dr. Goodrich said.

Don't be surprised this tornado season when you hear EF instead of F as a measure of tornadic strength.

For more information on the EF Scale, check out the following links:

  • www.wbko.com/unclassified/1353127.html
  • www.spc.noaa.gov/efscale/
  • www.wdtb.noaa.gov/courses/EF-scale/lesson1/player.html


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