Enhanced Fujita Scale

In 1972, Dr. T. Theodore Fujita introduced his idea for rating tornadoes. His scale had two purposes:
          -Categorize each tornado by its intensity and size
          -Estimate a wind speed by the damage caused by the tornado

The scale was divided into 6 areas:
          -F0 = 40-72mph = Little Damage
          -F1 = 73-112mph = Moderate Damage
          -F2 = 113-157mph = Considerable Damage
          -F4 = 158-206mph = Severe Damage
          -F4 = 207-260mph = Devastating Damage
          -F5 = 261-318mph = Incredible Damage

After many studies, it was seen that actual wind speeds required to inflict this damage was less than what is indicated. The original F Scale didn't take into account the quality of consturction of sturctures. In 1992, Dr. Fujita, then retired, worked on modifying the scale, but the NWS didn't make it a priority.

As you see, the F Scale is actually designed to go up to an F12, which would estimate wind speeds around 738 mph -- the speed of sound!

However, in 2006, the F Scale was revised, and the Enhanced Fujita Scale (EF Scale) was born. Introduced in 2007, it is believed that this new scale is much more accurate at estimating wind speed. It now takes into consideration many more types of structures, vegetation, degrees of damage, and quality of construction. What remains the same? It remains an evaluation of the damage caused by a tornado and it is only estimating wind speeds.

          EF0
          65-85mph Light Damage
          Peels surface off some roofs; some damage to gutters or siding;
          branches broken off trees; shallow-rooted trees pushed over.

          EF1
          86-110mph Moderate Damage
          Roofs severely stripped; mobile homes overturned or badly
          damaged; loss of exterior doors; windows and other glass broken.

          EF2
          111-135mph Considerable Damage
          Roofs torn off well-constructed houses; foundations of frame homes
          shifted; mobile homes completely destroyed; large trees snapped
          or uprooted; light-object missiles generated; cars lifted off ground.

          EF3
          136-165mph Severe Damage
          Entire stories of well-constructed houses destroyed; severe
          damage to large buildings such as shopping malls; trains
          overturned; trees debarked; heavy cars lifted off the ground and
          thrown; structures with weak foundations blown away some
          distance.

          EF4
          166-200mph Devastating Damage
          Well-constructed houses and whole frame houses completely
          leveled; cars thrown and small missiles generated.

          EF5
          >201mph Incredible Damage
          Strong frame houses leveled off foundations and swept away;
          automobile-sized missiles fly through the air in excess of 100 m
          (109 yd); high-rise buildings have significant structural deformation;
          incredible phenomena will occur.

          So far only two EF5 tornadoes have been recorded since the
          Enhanced Fujita Scale was introduced on February 1, 2007.
          They were the May 4, 2007 tornado that struck Greensburg, KS and the
          May 25, 2008 tornado that struck the Parkersburg/New Hartford, IA area.