The E-F scale is fairly new. It first became operational on February 1, 2007.
You were right-- the 'F' stands for Fujita, and that 'E' stands for "enhanced." It's now known as the Enhanced Fujita Scale.
The original Fujita Scale was developed by T. Theodore Fujita and was put into use in 1973. It was later revised to align wind speeds more closely with associated storm damage.
Here's a look at what those revised ratings:
- An EF-0 has "light damage" with wind speeds 65 to 85 miles per hour.
- An EF-1 has "moderate damage" with wind 86 to 110 miles per hour.
- An EF-2 has "considerable damage" with wind 111 to 135 miles per hour.
- An EF-3 has "severe damage" with wind 136 to 165 miles per hour.
- An EF-4 has "devastating damage" with wind 166 to 200 miles per hour
- An EF-5, which is very rare, causes "incredible damage" with wind above 200 miles per hour.