On the afternoon of Monday, May 20, 2013, a large and extremely powerful EF5 tornado ravaged Moore, Oklahoma, and adjacent areas, with peak winds estimated at 210 mph (340 km/h), killing 24 people (plus two indirect fatalities) and injuring 212 others. The tornado was part of a larger weather system that had produced several other tornadoes across the Great Plains over the previous two days, including five that struck portions of Central Oklahoma the day prior on May 19.

The tornado touched down just northwest of Newcastle at 2:56 p.m. CDT (19:46 UTC), and stayed on the ground for 39 minutes over a 17-mile (27 km) path, crossing through a heavily populated section of Moore. The tornado was 1.08 miles (1.74 km) wide at its peak. It followed a roughly similar track to the deadlier 1999 Bridge CreekMoore tornado, which was smaller in size but just as severe; however, very few homes and neither of the stricken schools in the area had purpose-built storm shelters in the intervening years since the earlier tornado struck Moore.

The Enhanced Fujita scale (abbreviated as EF-Scale) rates the intensity of tornadoes in some countries, including the United States and Canada, based on the severity of the damage they cause.

The Enhanced Fujita scale replaced the decommissioned Fujita scale that was introduced in 1971 by Ted Fujita. Operational use began in the United States on February 1, 2007, followed by Canada on April 1, 2013. It has also been proposed for use in France. The scale has the same basic design as the original Fujita scale—six intensity categories from zero to five, representing increasing degrees of damage. It was revised to reflect better examinations of tornado damage surveys, in order to align wind speeds more closely with associated storm damage. Better standardizing and elucidating what was previously subjective and ambiguous, it also adds more types of structures and vegetation, expands degrees of damage, and better accounts for variables such as differences in construction quality. An "EF-Unknown" (EFU) category was later added for tornadoes that cannot be rated due to a lack of damage evidence.The newer scale was publicly unveiled by the National Weather Service at a conference of the American Meteorological Society in Atlanta on February 2, 2006. It was developed from 2000 to 2004 by the Fujita Scale Enhancement Project of the Wind Science and Engineering Research Center at Texas Tech University, which brought together dozens of expert meteorologists and civil engineers in addition to its own resources.As with the Fujita scale, the Enhanced Fujita scale remains a damage scale and only a proxy for actual wind speeds. While the wind speeds associated with the damage listed have not undergone empirical analysis (such as detailed physical or any numerical modeling) owing to excessive cost, the wind speeds were obtained through a process of expert elicitation based on various engineering studies since the 1970s as well as from field experience of meteorologists and engineers. In addition to damage to structures and vegetation, radar data, photogrammetry, and cycloidal marks (ground swirl patterns) may be utilized when available.

The scale was used for the first time in the United States a year after its public announcement when parts of central Florida were struck by multiple tornadoes, the strongest of which were rated at EF3 on the new scale. It was used for the first time in Canada shortly after its implementation there when a tornado developed near the town on Shelburne, Ontario, on April 18, 2013, causing up to EF1 damage.