The Greensburg tornado was an EF5 on the Enhanced Fujita Scale, which is equivalent to an F5 on the original Fujita Scale.
It stands for "Enhanced Fujita" as it is a rating on the Enhanced Fujita Scale, and updated version of the Fujita scale, created by Tetsuya Fujita.
Both scales assess the intensity of a tornado based on the severity of the damage it causes. The ratings on the Fuijta and Enhanced Fujita scale are equivalent. For example a tornado rated F2 on the Fujita scale would probably be rated EF2 on the Enhanced Fujita scale.
The Fujita and Enhanced Fujita scales assesses damage caused by a tornado to assign a rating.
Enhanced Fujita
EF means "Enhanced Fujita" referring to the scale that is used, called the Enhanced Fujita Scale.
fujita scale now called enhanced fujita scale
The most powerful category of tornado is F5 on the Fujita scale or EF5 on the Enhanced Fujita Scale.
the fujita scale now called enhanced fujita scale
An "F0" category according to the Fujita scale or the EF0 category on the Enhanced Fujita scale.
by scale called the fujita scale or (enhanced fujita scale) to measure intensity or strength of a tornado based on the severity of damage.
The worst level a tornado can attain is F5 on the old Fujita scale or EF5 on the newer Enhanced Fujita scale.