There were over 50 tornadoes in Alabama on April 27, 2011 of varying intensity. Here are the estimated peak wind speeds for the most significant of those tornadoes.
Tuscaloosa-Birmingham tornado (EF4): 190 mph (306 km/h)
Hackleburg-Phil Campbell tornado (EF5): 210 mph (338 km/h)
Rainsville tornado (EF5): over 200 mph (322 km/h)
The wind speed of a tornado is inferred from the severity of the damage it inflicts.
The estimated wind speed of an EF0 tornado is 65-85 mph.
In most cases the wind speed of a tornado is estimated based on the severity of the damage it causes.
The actual maximum wind speed for a tornado is not known. The strongest wind ever recorded in a tornado was 302 mph.
Scientists usually use the severity of the damage a tornado causes to estimate its wind speed.
The largest tornado ever recorded was the El Reno, Oklahoma tornado of May 31, 2013. This tornado was 2.6 miles wide. Doppler radar measured a wind gust in the tornado at 296 mph, the second highest wind speed ever recorded in a tornado.
Tornado intensity is determined by damage, which is used to estimate wind speed. These wind speed estimates are used to sort a tornado into one of six categories from EF0 to EF5.
Wind speed is usually estimated based on the severity of damage that the tornado causes. In some cases it is measured by Doppler radar or, rarely, with an anemometer inside the tornado.
Scientists use the severity of damage that a tornado causes to estimate wind speed.
Wind speed estimates of an F2 tornado range from 113 to 157 mph. This was later adjusted to 111-135 mph for an EF2
An EF5 tornado has winds in excess of 200 mph.
An EF0 tornado has winds of 65-85 mph.