Roof coverings stripped; mobile homes overturned; windows broken. EF2 111–135 mph
post-storm based on the damage they leave behind. Reddit +2 The Enhanced Fujita (EF) Scale The EF Scale uses 28 different "damage indicators" (like specific building types or tree species) to estimate a tornado's wind speeds. NOAA National Severe Storms Laboratory +1 EF Rating Estimated 3-Second Gust (mph) Typical Damage Examples EF0 65–85 Branches broken, shallow-rooted trees pushed over EF1 86–110 Roof surfaces peeled off, mobile homes pushed or overturned EF2 111–135 Roofs torn off well-built houses, large trees snapped or uprooted EF3 136–165 Entire stories of well-constructed houses destroyed, heavy cars lifted EF4 166–200 Well-constructed houses leveled; structures with weak foundations blown away EF5 >200 Strong frame houses swept away; automobile-sized missiles fly through air Key Nuances in Tornado Rating 12 sites Severe Weather 101: Tornado Basics To determine the strength of a tornado, experts examine the damage it caused. From this information, we can estimate the wind spee... NOAA National Severe Storms Laboratory
The EF-Scale categories are based on 3-second wind gusts inferred from observed destruction: Wind Speed (mph) Typical Damage Weak: Minor roof damage, broken tree branches. EF1 Weak: Roofs peeled, mobile homes pushed off foundations. EF2 tornado ratings
Professionals check for construction flaws, such as missing anchor bolts or poor strapping, which can artificially downgrade or upgrade a rating.
Recognizing the limitations of the F-scale, the National Weather Service (NWS) in the United States, in collaboration with wind engineering researchers at Texas Tech University, introduced the Enhanced Fujita Scale in February 2007. NOAA National Severe Storms Laboratory +1 EF Rating
Raters look for the "worst-case scenario" within the damage path. They might find EF-1 damage to trees on one side of the street, EF-3 damage to a roof on the other, and an EF-5 sweep of a foundation in the center. The tornado is rated by its worst point, not its average.
Developed by Dr. Ted Fujita in 1971, this was the first systematic method for rating tornadoes based on damage. It used an F0 to F5 scale to estimate wind speeds. EF1 Weak: Roofs peeled, mobile homes pushed off foundations
Teams observe the structural failure level, noting if a building merely lost roof decking or suffered full foundation sweeping.
Tornado intensity assessment has evolved significantly from subjective damage descriptions to standardized engineering-based scales. This paper examines the history, application, and inherent limitations of tornado rating systems, focusing primarily on the Fujita Scale (F-scale) and its successor, the Enhanced Fujita Scale (EF-scale). While the EF-scale represents a substantial improvement through the incorporation of Damage Indicators (DIs) and Degrees of Damage (DoD), this analysis concludes that tornado ratings remain a proxy for intensity rather than a direct measurement. Challenges such as the availability of robust structures, rating inconsistencies, and the influence of non-meteorological factors continue to affect the reliability of the climatological tornado record.
A tornado that sweeps away a flimsy barn might only be rated an EF-2 or EF-3. A tornado that sweeps away a fortified concrete structure might be rated an EF-5. It is no longer just about the debris; it is about the construction quality.