The EF Scale is the common way of rating a tornado's strength. The "E" stands for "enhanced while the "F" stands for "Fujita." Dr. Fujita came up with the original "F" Scale which was develope in 1971 and rated a tornado on a scale of 0 to 5. In 2007, the National Weather Service adopted the EF-Scale to better reflect the examinations of tornado damage surveys.
After storms cause damage, typically the National Weather Service will do a survey. During that time the surveyors will first confirm whether or not a tornado did the damage, or it it may have been damaging winds. Once a tornado is confirmed, the extent of the damage is noted. Depending on that extent, the National Weather Service can assign a wind speed to the tornado as well as a rating on the EF Scale. Below is a look at the wind speeds and damage associated with each part of the EF Scale.
EF-0 (Winds of 65 to 85 mph)
Typically there is minor damage from an EF-0 tornado. That includes shingles blown off or parts of a roof peeled back along with damage to gutters or siding. Trees will typically have brances broken off and trees with shallow roots can be toppled.
EF-1 (Winds of 86 to 110 mph)
Damage from an EF-1 tornado is considered to be "moderate". Windows are broken out on homes and exterior doors are damaged or even lost. Mobile homes will be overturned or badly damaged.
EF-2 (Winds of 111-135 mph)
Damage from an EF-2 tornado is "considerable." Roofs will be torn completely off of well constructed homes and some homes will be shifted off their foundations. Mobile homes will be destroyed. Large trees are snapped or uprooted and cars can be tossed.
EF-3 (Winds of 136-165 mph)
Damage from an EF-3 tornado is "severe" with entire stories of well constructed homes destroyed. Significant damage will be done to large buildings. Weak foundations can be blown away and trees begin to lose their bark.
EF-4 (Winds of 166-200 mph)
Ef-4 tornadoes cause extreme damage. Well constructed homes are leveled with cars thrown significant distances. Top story exterior wall of masonry building would likely collapse.
EF-5 (Winds over 200 mph)
Incredible or massive damage is what EF-5 tornadoes do. Well constructed homes are swept away and steel reinforced concrete structures are critcally damaged. High rise buildings sustain severe structural damage. Trees are completely debarked and stripped of branches and could be snapped.