Tornados are among the most destructive and unpredictable natural disasters that can threaten your home and family. The strength of tornado vortices are rated on a scale called the Enhanced Fujita Scale. This scale measures storms on the basis of the amount of damage done to various structures and natural features. For this reason, the actual force of a particular tornado cannot be determined until after it has passed. However, projections can be made based on wind speed and weather conditions that give the public an idea of how to prepare when a storm is eminent. Emergency broadcasts often predict tornado strength using the Enhance Fujita Scale, so it is vital to have an understanding of what these ratings mean in order to be ready and stay safe.
Based on the Fujita Scale, which was devised by meteorologist Ted Fujita in 1971, the Enhanced Fujita Scale has been in use in the United States since 2007. It is the result of a body of scientific research conducted over the past 40 years that compares actual wind speeds within a tornado funnel to damage seen after the storm passes. The enhanced scale takes into account more detail regarding the type of materials and construction design of structures and vegetation to give a more accurate analysis of tornado strength.
The scale classifies tornados into six categories, EF-0 through EF-5, in increasing order of damage severity. At the lowest end, EF-0, wind speeds are only around 65-85 miles per hour, and damage is very minimal, such as gutters being loosened and branches being broken from trees. Additionally, EF-0 is given to any confirmed tornado that does not cause any damage to buildings or other private property. More than half of all tornados in the U.S. fall into the EF-0 category. EF-1 tornados cause moderate damage, breaking glass in windows or overturning mobile homes. Wind speeds range from 86 to 110 mph. Damage from EF-2 storms is considerable, with winds 111-135 mph and homes shifted off of their foundations, well-built roofs destroyed, and large trees uprooted. Moving up the scale, EF-3 tornadoes contain winds moving at 136 to 165 miles per hour. Storms of this strength result in severe damage to large commercial buildings and well-constructed homes alike, cause trains to be overturned, and lift heavy cars into the air and throw them some distance. Representing less than 1% of all tornados, damage from EF-4 storms is considered extreme. Winds range from 166-200 mph, completely leveling all wood frame buildings. The rarest of all, the EF-5 tornado, is a mind-blowingly powerful event. Winds exceed 200 miles per hour, and in fact, wind speeds from an EF-5 storm have been recorded at over 300 mph. Damage is massive. Steel-frame and concrete structures are severely damaged, and any other types of construction are annihilated. Often, spectacular phenomena are seen in the aftermath of an EF-5 tornado, such as whole trees being driven into concrete walls or cars and trucks bent in half.
Because tornados can form and intensify very rapidly, it is essential to heed warnings and take cover if conditions that signal tornado activity are present. Though actual Enhanced Fujita Scale ratings are based on damage assessments, and thus are tabulated after a storm has passed, projections can be made before and during a storm. EF-scale categories are sometimes included in severe weather warning broadcasts. Based on knowledge of wind speeds on the Enhanced Fujita Scale, you can estimate the eminent danger to your life and property, and follow your emergency preparedness plan to ensure your family’s safety.