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The Enhanced Fujita scale (abbreviated as EF-Scale) rates
tornado intensity Tornado intensity can be measured by ''in situ'' or remote sensing measurements, but since these are impractical for wide-scale use, intensity is usually inferred by proxies, such as damage. The Fujita scale, Enhanced Fujita scale, and the Inte ...
based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, China, and Mongolia. The Enhanced Fujita scale replaced the decommissioned
Fujita scale The Fujita scale (F-Scale; ), or Fujita–Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is deter ...
that was introduced in 1971 by
Ted Fujita was a Japanese-American meteorologist whose research primarily focused on severe weather. His research at the University of Chicago on severe thunderstorms, tornadoes, hurricanes, and typhoons revolutionized the knowledge of each. Although he is ...
. 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 speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed ...
s 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 Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characte ...
, 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 The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
at a conference of the
American Meteorological Society The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance th ...
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 The National Wind Institute (NWI) at Texas Tech University (TTU) was established in December 2012, and is intended to serve as Texas Tech University's intellectual hub for interdisciplinary and transdisciplinary research, commercialization and educ ...
at
Texas Tech University Texas Tech University (Texas Tech, Tech, or TTU) is a public research university in Lubbock, Texas. Established on , and called Texas Technological College until 1969, it is the main institution of the five-institution Texas Tech University Sy ...
, which brought together dozens of expert
meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...
s 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 In science, engineering, and research, expert elicitation is the synthesis of opinions of authorities of a subject where there is uncertainty due to insufficient data or when such data is unattainable because of physical constraints or lack of res ...
based on various engineering studies since the 1970s as well as from the 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 of Shelburne, Ontario, on April 18, 2013, causing up to EF1 damage.


Parameters

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.


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. The links in the right column of the following table describe the degrees of damage for the damage indicators listed in each row.


Differences from the Fujita scale

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. The old scale lists an F5 tornado as wind speeds of , while the new scale lists an EF5 as a tornado with winds above , 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 A strip mall, strip center or strip plaza is a type of shopping center common in North America where the stores are arranged in a row, with a sidewalk in front. Strip malls are typically developed as a unit and have large parking lots in front. ...
", 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. 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. 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.


Rating classifications

For purposes such as
tornado climatology Tornadoes have been recorded on all continents except Antarctica. They are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as we ...
studies, Enhanced Fujita scale ratings may be grouped into classes. Classifications are also used by NOAA's
Storm Prediction Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...
to determine whether the tornado was "significant". This same classification is also used by the National Weather Service. The table shows other variations of the tornado rating classifications based on certain areas.


See also

* Beaufort scale *
International Fujita scale The International Fujita scale (abbreviated as IF-Scale) rates the intensity of tornadoes and other wind events based on the severity of the damage they cause. It is used by the European Severe Storms Laboratory (ESSL) and is being worked on by va ...
* Saffir–Simpson hurricane wind scale *
Severe weather terminology (United States) This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United ...
*
TORRO scale The TORRO tornado intensity scale (or T-Scale) is a scale measuring tornado intensity between T0 and T11. It was proposed by Terence Meaden of the Tornado and Storm Research Organisation (TORRO), a meteorological organisation in the United Kingdo ...
*
Tornado intensity and damage Tornado intensity can be measured by ''in situ'' or remote sensing measurements, but since these are impractical for wide-scale use, intensity is usually inferred by proxies, such as damage. The Fujita scale, Enhanced Fujita scale, and the Int ...
*
Wind engineering Wind engineering is a subset of mechanical engineering, structural engineering, meteorology, and applied physics that analyzes the effects of wind in the natural and the built environment and studies the possible damage, inconvenience or benefits ...
*
Lists of tornadoes and tornado outbreaks These are some notable tornadoes, tornado outbreaks, and tornado outbreak sequences that have occurred around the globe. # ''Exact death and injury counts are not possible; especially for large events and events before 1955.'' # ''Prior to 1950 in ...
** List of F4 and EF4 tornadoes **
List of F5 and EF5 tornadoes This is a list of tornadoes which have been officially or unofficially labeled as F5, EF5, T10-T11, IF5, or an equivalent rating, the highest possible ratings on the various tornado intensity scales. These scales – the Fujita scale, the Enhance ...


References

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External links

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National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
*
NOAA National Weather Service Improves Tornado Rating System
at NOAA News
The Enhanced Fujita Scale (EF Scale)
at
Storm Prediction Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...
*
EF-Scale Training
{{Webarchive, url=https://web.archive.org/web/20170621062710/http://wdtb.noaa.gov/courses/EF-scale/ , date=June 21, 2017 at The Warning Decision Training Branch of
National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
(NWS) *
The Enhanced Fujita Tornado Scale
at
National Climatic Data Center The United States National Climatic Data Center (NCDC), previously known as the National Weather Records Center (NWRC), in Asheville, North Carolina, was the world's largest active archive of weather data. Starting as a tabulation unit in New Or ...
*
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 The National Wind Institute (NWI) at Texas Tech University (TTU) was established in December 2012, and is intended to serve as Texas Tech University's intellectual hub for interdisciplinary and transdisciplinary research, commercialization and educ ...
at
Texas Tech University Texas Tech University (Texas Tech, Tech, or TTU) is a public research university in Lubbock, Texas. Established on , and called Texas Technological College until 1969, it is the main institution of the five-institution Texas Tech University Sy ...
)
Symposium on the F-Scale and Severe-Weather Damage Assessment
at
American Meteorological Society The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance th ...

A Guide to F-Scale Damage Assessment
MetEd,
University Corporation for Atmospheric Research The University Corporation for Atmospheric Research (UCAR) is a US nonprofit consortium of more than 100 colleges and universities providing research and training in the atmospheric and related sciences. UCAR manages the National Center for Atmosph ...

Mitigation Assessment Team Report: Midwest Tornadoes of May 3, 1999
(
Federal Emergency Management Agency The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Ex ...
) Hazard scales Wind Tornado Scales in meteorology