Enhanced Fujita scale

The Enhanced Fujita scale replaced the decommissioned Fujita scale that was introduced in 1971 by Ted Fujita.^[4] Operational use began in the United States on February 1, 2007, followed by Canada on April 1, 2013, who uses a modified verion known as the CEF-scale.^{[5][6][7][8][9]} It has also been in use in France since 2008, albeit modified slightly by using damage indicators that take into account French construction standards, native vegetation, and the use of metric units.^[10] Similarly, the Japanese implementation of the scale is also modified along similar lines; the Japanese variant is referred to locally in Japan as the JEF or Japanese Enhanced Fujita Scale.^[11] The scale is also used unofficially in other countries, such as China.^[12]

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.^[13]

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.

In November 2022, a research paper was published that revealed a more standardized EF-scale was in the works. This newer scale is expected to combine and create damage indicators, and introduce new methods of estimating windspeeds. Some of these newer methods include mobile doppler radar and forensic engineering.^[14]

In 2024, Anthony W. Lyza, Matthew D. Flournoy, and A. Addison Alford, researchers with the National Severe Storms Laboratory, Storm Prediction Center, CIWRO, and the University of Oklahoma's School of Meteorology, published a paper stating, ">20% of supercell tornadoes may be capable of producing EF4–EF5 damage".^[15]

The seven categories for the EF scale are listed below, in order of increasing intensity. Although the wind speeds and photographic damage examples have been updated, the damage descriptions given are based on those from the Fujita scale, which are more or less still accurate. However, for the actual EF scale in practice, damage indicators (the type of structure which has been damaged) are predominantly used in determining the tornado intensity.^[16]

Scale	Wind speed estimate[17]		Frequency[18]	Potential Damage	Example of damage
	mph	km/h
EFU	N/A	N/A	3.11%	No surveyable damage. Intensity cannot be determined due to a lack of information. This rating applies to tornadoes that traverse areas with no damage indicators, cause damage in an area that cannot be accessed by a survey, or cause damage that cannot be differentiated from that of another tornado.[3]	N/A
EF0	65–85	105–137	52.82%	Minor damage. Small trees are blown down and bushes are uprooted. Shingles are ripped off roofs, windows in cars and buildings are blown out, medium to large branches snapped off of large trees, sheds are majorly damaged, and loose small items are tossed and blown away (i.e. lawn chairs, plastic tables, sports equipment, mattresses). Barns are damaged. Paper and leaves lifted off the ground.[19]
EF1	86–110	138–177	32.98%	Moderate damage Roofs stripped from shingles or planting. Small areas of roof may be blown off house. Doors and garage doors blown in, siding ripped off houses, mobile homes flipped or rolled onto their sides, small trees uprooted, large trees snapped or blown down, telephone poles snapped, outhouses and sheds blown away. Cars occasionally flipped or blown over, and moderate roof and side damage to barns. Corn stalks slightly bent and stripped of leaves.
EF2	111–135	178–217	8.41%	Considerable damage Whole roofs ripped off frame houses, interiors of frame homes damaged, and small, medium, and large trees uprooted. Weak structures such as barns, mobile homes, sheds, and outhouses are completely destroyed. Cars are lifted off the ground.
EF3	136–165	218–266	2.18%	Severe damage Roofs and numerous outside walls blown away from frame homes, all trees in its path uprooted or lofted. Two-story homes have their second floor destroyed, high-rises have many windows blown out, radio towers blown down, metal buildings (e.g. factories, power plants, construction sites, etc.) are heavily damaged, sometimes completely destroyed. Large vehicles such as tractors, buses, and forklifts are blown from their original positions. Trains can be flipped or rolled onto their sides. Severe damage to large structures such as shopping malls.
EF4	166–200	267–322	0.45%	Devastating damage Trees are partially debarked, cars are mangled and thrown in the air, frame homes are completely destroyed and some may be swept away, moving trains blown off railroad tracks, and barns are leveled. High-rises are significantly damaged.
EF5	201+	323+	0.05%	Incredible damage Nearly all buildings aside from heavily built structures are destroyed. Cars are mangled and thrown hundreds, possibly thousands of yards away. Frame homes, brick homes, and small businesses, are swept away, trees debarked, corn stalks flattened or ripped out of the ground, skyscrapers sustain major structural damage, grass ripped out of the ground. Wood and any small solid material become dangerous projectiles.

Damage indicators and degrees of damage

The EF scale currently has 28 damage indicators (DI), or types of structures and vegetation, each with a varying number of degrees of damage (DoD). Each structure has a maximum DoD value, which is given by total destruction. Lesser damage to a structure will yield lower DoD values.^[20] The links in the right column of the following table describe the degrees of damage for the damage indicators listed in each row.

The new scale takes into account the quality of construction and standardizes different kinds of structures. The wind speeds on the original scale were deemed by meteorologists and engineers as being too high, and engineering studies indicated that slower winds than initially estimated cause the respective degrees of damage.^[49] The old scale lists an F5 tornado as wind speeds of 261–318 mph (420–512 km/h), while the new scale lists an EF5 as a tornado with winds above 200 mph (322 km/h), found to be sufficient to cause the damage previously ascribed to the F5 range of wind speeds. None of the tornadoes in the United States recorded before February 1, 2007, will be re-categorized.

Essentially, there is no functional difference in how tornadoes are rated. The old ratings and new ratings are smoothly connected with a linear formula. The only differences are adjusted wind speeds, measurements of which were not used in previous ratings, and refined damage descriptions; this is to standardize ratings and to make it easier to rate tornadoes which strike few structures. Twenty-eight Damage Indicators (DI), with descriptions such as "double-wide mobile home" or "strip mall", are used along with Degrees of Damage (DoD) to determine wind estimates. Different structures, depending on their building materials and ability to survive high winds, have their own DIs and DoDs. Damage descriptors and wind speeds will also be readily updated as new information is learned.^[20] Some differences do exist between the two scales in the ratings assigned to damage. An EF5 rating on the new scale requires a higher standard of construction in houses than does an F5 rating on the old scale. So, the complete destruction and sweeping away of a typical American frame home, which would likely be rated F5 on the Fujita scale, would be rated EF4 or lower on the Enhanced Fujita scale.^[50]

Since the new system still uses actual tornado damage and similar degrees of damage for each category to estimate the storm's wind speed, the National Weather Service states that the new scale will likely not lead to an increase in the number of tornadoes classified as EF5. Additionally, the upper bound of the wind speed range for EF5 is open—in other words, there is no maximum wind speed designated.^[16]

For purposes such as tornado climatology studies, Enhanced Fujita scale ratings may be grouped into classes.^[51][52][53] Classifications are also used by NOAA's Storm Prediction Center to determine whether the tornado was "significant". This same classification is also used by the National Weather Service. The National Weather Service of Quad Cities use a modified EF scale wording, which gives a new term for each rating on the scale, going from weak to catastrophic.^[54]

The table shows other variations of the tornado rating classifications based on certain areas.

• Edwards, Roger; J. G. LaDue; J. T. Ferree; K. Scharfenberg; C. Maier; W. L. Coulbourne (2013). "Tornado Intensity Estimation: Past, Present, and Future". Bull. Amer. Meteor. Soc. 94 (5): 641–53. Bibcode:2013BAMS...94..641E. doi:10.1175/BAMS-D-11-00006.1. S2CID 7842905.

Wikimedia Commons has media related to Enhanced Fujita Scale.

• National Oceanic and Atmospheric Administration
  • NOAA National Weather Service Improves Tornado Rating System at NOAA News
  • The Enhanced Fujita Scale (EF Scale) at Storm Prediction Center
  • EF-Scale Training Archived June 21, 2017, at the Wayback Machine at The Warning Decision Training Branch of National Weather Service (NWS)
  • The Enhanced Fujita Tornado Scale at National Climatic Data Center
  • The Tornado: An Engineering-Oriented Perspective (NWS SR147)
  • A Guide for Conducting Convective Windstorm Surveys (NWS SR146)
• Fujita Scale Enhancement Project (Wind Science and Engineering Research Center at Texas Tech University)
• Symposium on the F-Scale and Severe-Weather Damage Assessment at American Meteorological Society
• A Guide to F-Scale Damage Assessment, MetEd, University Corporation for Atmospheric Research
• Mitigation Assessment Team Report: Midwest Tornadoes of May 3, 1999 (Federal Emergency Management Agency)