Sunday, November 16, 2008

EF-Scale for Tornado Ratings


If you've been following news coverage of this weekend's tornadic thunderstorms that came across Johnston and Wilson counties, you're hearing about the strength of these tornadic winds expressed as 'E-F' instead of 'F' (for example, 'EF-2' rather than 'F-2').

Some of you may be wondering why thats happening in the news these days. After all, its supposed to be F-1, F-2, etc. Right? Thats how it was when you were growing up.

You're right as far as it having *been* classified that way before, but in 2007 meteorologists started using a new scale. Its still based on the Fujita Scale (the 'F' scale) but this is called the 'Enhanced Fujita' scale.
The scale still represents increasing degrees of damage from tornadic winds.
It was revised to reflect what was being seen out in the field when surveyors examined the aftermath of tornadoes. It also had to start taking into account more types of structures, different building materials and construction quality. It also has additional categories of vegetation.
In other words while storms may stay the same, the things they encounter may change over time. The science which we use to understand these storms also evolves over time.

The Storm Prediction Center has a wealth of information for you on this subject. Here's the link.

http://www.spc.noaa.gov/efscale/

PD

1 comment:

Art said...

I was curious about that. Thanks for enlightening me!

af