Enhanced Fujita scale

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Enhanced Fujita Scale
EFUUnknownNo surveyable damage
EF065–85 mphLight damage
EF186–110 mphModerate damage
EF2111–135 mphConsiderable damage
EF3136–165 mphSevere damage
EF4166–200 mphDevastating damage
EF5>200 mphIncredible damage
The National Weather Service's arrow showing the EF scale. This includes a description word for each level of the scale. The National Weather Service Six-Step Wording for the Enhanced Fujita Scale.jpg
The National Weather Service’s arrow showing the EF scale. This includes a description word for each level of the scale.

The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, France, China, and Mongolia.[ citation needed ]

Contents

The Enhanced Fujita scale replaced the decommissioned Fujita scale that was introduced in 1971 by Ted Fujita. [1] Operational use began in the United States on February 1, 2007, followed by Canada on April 1, 2013. [2] [3] [4] 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. [5] 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. [6]

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. [7]

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 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. [8]

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. [9]

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". [10]

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. [11]

ScaleWind speed estimate [12] Frequency [13] Potential Damage [6]Example of damage
mphkm/h
EFUN/AN/A3.11%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. [6]
N/A
EF065–85105–13752.82%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. [14]
Sunset Beach EF0 damage.jpg
EF186–110138–17732.98%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.
 EF1 damage Richardson, Texas.jpg
EF2111–135178–2178.41%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.
 WelchEF2Damage2012.jpg
EF3136–165218–2662.18%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.
 January 23, 2012, Center Point, Alabama tornado damage.JPG
EF4166–200267–3220.45%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.
 Moore, OK EF4 damage DOD9.jpg
EF5201+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.
 EF5damageMoore2013.jpg

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

DI No.Damage indicator (DI)Maximum degrees of damage
1Small barns or farm outbuildings (SBO)8 [16]
2One- or two-family residences (FR12)10 [17]
3Manufactured home – single wide (MHSW)9 [18]
4Manufactured home – double wide (MHDW)12 [19]
5Apartments, condos, townhouses [three stories or less] (ACT)6 [20]
6Motel (M)10 [21]
7Masonry apartment or motel building (MAM)7 [22]
8Small retail building [fast-food restaurants] (SRB)8 [23]
9Small professional building [doctor's office, branch banks] (SPB)9 [24]
10Strip mall (SM)9 [25]
11Large shopping mall (LSM)9 [26]
12Large, isolated retail building [Wal-Mart, Home Depot] (LIRB)7 [27]
13Automobile showroom (ASR)8 [28]
14Automobile service building (ASB)8 [29]
15Elementary school [single-story; interior or exterior hallways] (ES)10 [30]
16Junior or senior high school (JHSH)11 [31]
17Low-rise building [1–4 stories] (LRB)7 [32]
18Mid-rise building [5–20 stories] (MRB)10 [33]
19High-rise building [more than 20 stories] (HRB)10 [34]
20Institutional building [hospital, government or university building] (IB)11 [35]
21Metal building system (MBS)8 [36]
22Service station canopy (SSC)6 [37]
23Warehouse building [tilt-up walls or heavy-timber construction] (WHB)7 [38]
24Electrical transmission lines (ETL)6 [39]
25Free-standing towers (FST)3 [40]
26Free-standing light poles, luminary poles, flag poles (FSP)3 [41]
27Trees: hardwood (TH)5 [42]
28Trees: softwood (TS)5 [43]

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. [44] 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. [15] 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. [45]

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. [11]

Rating classifications

Tornado rating classifications
EF0EF1EF2EF3EF4EF5
WeakModerateStrongSevereExtremeCatastrophic
WeakStrongViolent
Significant
Intense

For purposes such as tornado climatology studies, Enhanced Fujita scale ratings may be grouped into classes. [46] [47] [48] 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. [49]

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

See also

Related Research Articles

<span class="mw-page-title-main">Tornado</span> Violently rotating column of air in contact with both the Earths surface and a cumulonimbus cloud

A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km (62 mi).

The Fujita scale, or Fujita–Pearson 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 determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns, weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings.

<span class="mw-page-title-main">Tornado records</span> List of world records related to tornadoes

This article lists various tornado records. The most "extreme" tornado in recorded history was the Tri-State tornado, which spread through parts of Missouri, Illinois, and Indiana on March 18, 1925. It is considered an F5 on the Fujita Scale, even though tornadoes were not ranked on any scale at the time. It holds records for longest path length at 219 miles (352 km), longest duration at about 3+1⁄2 hours, and it held the fastest forward speed for a significant tornado at 73 mph (117 km/h) anywhere on Earth until 2021. In addition, it is the deadliest single tornado in United States history with 695 fatalities. It was also the third most costly tornado in history at the time, but has been surpassed by several others when non-normalized. When costs are normalized for wealth and inflation, it still ranks third today.

The TORRO tornado intensity 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 Kingdom, as an extension of the Beaufort scale.

<span class="mw-page-title-main">Tornado intensity</span> Measurement of strength and severity of tornadoes

Tornado intensity is the measure of wind speeds and potential risk produced by a 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 International Fujita scale rate tornadoes by the damage caused. In contrast to other major storms such as hurricanes and typhoons, such classifications are only assigned retroactively. Wind speed alone is not enough to determine the intensity of a tornado. An EF0 tornado may damage trees and peel some shingles off roofs, while an EF5 tornado can rip well-anchored homes off their foundations, leaving them bare— even deforming large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns may also be analyzed to determine the intensity and assign a rating.

<span class="mw-page-title-main">Tornado outbreak of April 1977</span> Tornado outbreak in the United States

A violent severe weather outbreak struck the Southeast on April 4–5, 1977. A total of 22 tornadoes touched down with the strongest ones occurring in Mississippi, Alabama, and Georgia. The strongest was a catastrophic F5 tornado that struck the northern Birmingham, Alabama, suburbs during the afternoon of Monday, April 4. In addition to this tornado, several other tornadoes were reported from the same system in the Midwest, Alabama, Georgia, Mississippi and North Carolina. One tornado in Floyd County, Georgia, killed one person, and another fatality was reported east of Birmingham in St. Clair County. In the end, the entire outbreak directly caused 24 deaths and 158 injuries. The storm system also caused the crash of Southern Airways Flight 242, which killed 72 and injured 22.

<span class="mw-page-title-main">2007 Elie tornado</span> Canadas only F5 tornado

During the evening of June 22, 2007, a powerful F5 tornado struck the town of Elie, in the Canadian province of Manitoba. It was part of a small two-day tornado outbreak that occurred in the area and reached a maximum width of 150 yards (140 m). The tornado was unusual because it caused the extreme damage during its roping out stage at a mere 35 yards (32 m) in width and moved extremely slowly and unpredictably. The tornado tracked primarily southeast, as opposed to the usual northeast, and made multiple loops and sharp turns. Because Environment Canada adopted the Enhanced Fujita scale in 2013, there will be no more tornadoes with an F5 rating, making this tornado the first and last confirmed F5 tornado in Canada.

<span class="mw-page-title-main">Tornado outbreak of February 21–22, 1971</span> Catastrophic tornado outbreak in the Mississippi Delta

On February 21–22, 1971, a devastating tornado outbreak, colloquially known as the Mississippi Delta outbreak, struck portions of the Lower Mississippi and Ohio River valleys in the Southern and Midwestern United States. The outbreak generated strong tornadoes from Texas to Ohio and North Carolina. The two-day severe weather episode produced at least 19 tornadoes, and probably several more, mostly brief events in rural areas; killed 123 people across three states; and wrecked entire communities in the state of Mississippi. The strongest tornado of the outbreak was an F5 that developed in Louisiana and crossed into Mississippi, killing 48 people, while the deadliest was an F4 that tracked across Mississippi and entered Tennessee, causing 58 fatalities in the former state. The former tornado remains the only F5 on record in Louisiana, while the latter is the deadliest on record in Mississippi since 1950. A deadly F4 also affected other parts of Mississippi, causing 13 more deaths. Other deadly tornadoes included a pair of F3s—one each in Mississippi and North Carolina, respectively—that collectively killed five people.

On June 3–4, 1958, a destructive tornado outbreak affected the Upper Midwestern United States. It was the deadliest tornado outbreak in the U.S. state of Wisconsin since records began in 1950. The outbreak, which initiated in Central Minnesota, killed at least 28 people, all of whom perished in Northwestern Wisconsin. The outbreak generated a long-lived tornado family that produced four intense tornadoes across the Eau Claire–Chippewa Falls metropolitan area, primarily along and near the Chippewa and Eau Claire rivers. The deadliest tornado of the outbreak was a destructive F5 that killed 21 people and injured 110 others in and near Colfax, Wisconsin.

<span class="mw-page-title-main">Tornadoes in the United States</span>

Tornadoes are more common in the United States than in any other country or state. The United States receives more than 1,200 tornadoes annually—four times the amount seen in Europe. Violent tornadoes—those rated EF4 or EF5 on the Enhanced Fujita Scale—occur more often in the United States than in any other country.

<span class="mw-page-title-main">2011 Tuscaloosa–Birmingham tornado</span> 2011 tornado in Alabama, U.S.A.

During the late afternoon and early evening of April 27, 2011, a violent, high-end EF4 multiple-vortex tornado destroyed portions of Tuscaloosa and Birmingham, Alabama, as well as smaller communities and rural areas between the two cities. It is one of the costliest tornadoes on record, and was one of the 360 tornadoes in the 2011 Super Outbreak, the largest tornado outbreak in United States history. The tornado reached a maximum path width of 1.5 miles (2.4 km) during its track through Tuscaloosa, and again when it crossed I-65 north of Birmingham, attaining estimated wind speeds of 190 mph (310 km/h) shortly after passing through the city. It then went on to impact parts of Birmingham at high-end EF4 intensity before dissipating. This was the third tornado to strike the city of Tuscaloosa in the past decade, and the second in two weeks.

The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.

The International Fujita 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 various other organizations including Deutscher Wetterdienst (DWD) and State Meteorological Agency (AEMET). The scale is intended to be analogous to the Fujita and Enhanced Fujita scales, while being more applicable internationally by accounting for factors such as differences in building codes.

<span class="mw-page-title-main">2011 El Reno–Piedmont tornado</span> 2011 EF-5 tornado in Oklahoma

The 2011 El Reno–Piedmont tornado was a long-tracked, deadly EF5 tornado that struck central Oklahoma on the evening of May 24, 2011. The tornado impacted areas near or within the communities of El Reno, Piedmont, and Guthrie, killing nine and injuring 181. After producing incredible damage in several locations along a path of over 60 mi (97 km), the El Reno–Piedmont tornado was given a rating of EF5, the highest category on the Enhanced Fujita scale, and was found by mobile radar to have possessed possible wind speeds of up to 295 mph (475 km/h). It was the first tornado rated EF5 or F5 to strike Oklahoma since the 1999 Bridge Creek–Moore tornado.

References

  1. ↑ Fujita, T. Theodore (February 1971) "Proposed characterization of tornadoes and hurricanes by area and intensity". SMRP (Satellite and Mesometeorology Research Project) Research Paper 91 (Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA) 42 pages.
  2. ↑ "Fujita Tornado Damage Scale". www.spc.noaa.gov.
  3. ↑ "Tornado Scale - The Enhanced Fujita Scale | TornadoFacts.net". www.tornadofacts.net.
  4. ↑ "Enhanced Fujita Scale". Environment Canada. May 10, 2013.
  5. ↑ "Intensité des tornades : l'Échelle améliorée de Fujita - Pédagogie - Comprendre les orages - Keraunos - Observatoire français des tornades et orages violents".
  6. 1 2 Murphy, John D. (July 9, 2018). "National Weather Service Instruction 10-1605" (PDF). National Weather Service. pp. A–74–75. Retrieved November 29, 2019.
  7. ↑ "Enhanced Fujita Scale - Tornado Damage Scale". factsjustforkids.com. Retrieved June 14, 2019.
  8. ↑ "Tornado to Be 1st Assessed by New Scale". The Washington Post. Associated Press. February 2, 2007. Retrieved July 11, 2009.
  9. ↑ Marshall, Tim & Brown-Giammanco, Tanya & Krautwurst, Samantha & Toledo, Nicholas. (2022). On the Current Revision of the Enhanced Fujita (EF) Scale.
  10. ↑ Lyza, Anthony W.; Flournoy, Matthew D.; Alford, A. Addison (March 19, 2024). "Comparison of Tornado Damage Characteristics to Low-Altitude WSR-88D Radar Observations and Implications for Tornado Intensity Estimation" (Academic publication). Monthly Weather Review . National Oceanic and Atmospheric Administration and University of Oklahoma via the American Meteorological Society. doi:10.1175/MWR-D-23-0242.1 . Retrieved March 19, 2024.
  11. 1 2 "The Enhanced Fujita Scale (EF Scale)". Storm Prediction Center. February 1, 2007. Retrieved June 21, 2009.
  12. ↑ "Enhanced F Scale for Tornado Damage". Storm Prediction Center. Retrieved June 21, 2009.
  13. ↑ "Storm Prediction Center WCM Data". Storm Prediction Center. Retrieved September 15, 2021.
  14. ↑ "Garrett's Blog: Mobile Home Tornado Risk". 5newsonline.com. February 28, 2013. Retrieved September 30, 2020.
  15. 1 2 McDonald, James; Kishor C. Mehta (October 10, 2006). A recommendation for an Enhanced Fujita scale (EF-Scale) (PDF). Lubbock, Texas: Wind Science and Engineering Research Center, Texas Tech University . Retrieved May 21, 2013.
  16. ↑ c:File:EF DI1 (SBO).jpg
  17. ↑ c:File:EF DI2 (FR12).jpg
  18. ↑ c:File:EF DI3 (MHSW).jpg
  19. ↑ c:File:EF DI4 (MHDW).jpg
  20. ↑ c:File:EF DI5 (ACT).jpg
  21. ↑ c:File:EF DI6 (M).jpg
  22. ↑ c:File:EF DI7 (MAM).jpg
  23. ↑ c:File:EF DI8 (SRB).jpg
  24. ↑ c:File:EF DI9 (SPB).jpg
  25. ↑ c:File:EF DI10 (SM).jpg
  26. ↑ c:File:EF DI11 (LSM).jpg
  27. ↑ c:File:EF DI12 (LIRB).jpg
  28. ↑ c:File:EF DI13 (ASR).jpg
  29. ↑ c:File:EF DI14 (ASB).jpg
  30. ↑ c:File:EF DI15 (ES).jpg
  31. ↑ c:File:EF DI16 (JHSH).jpg
  32. ↑ c:File:EF DI17 (LRB).jpg
  33. ↑ c:File:EF DI18 (MROB).jpg
  34. ↑ c:File:EF DI19 (HROB).jpg
  35. ↑ c:File:EF DI20 (IB).jpg
  36. ↑ c:File:EF DI21 (MBS).jpg
  37. ↑ c:File:EF DI22 (SSC).jpg
  38. ↑ c:File:EF DI23 (WHB).jpg
  39. ↑ c:File:EF DI 24 (ETL).jpg
  40. ↑ c:File:EF DI25 (FST).jpg
  41. ↑ c:File:EF DI26 (FSP).jpg
  42. ↑ c:File:EF DI27 (TH).jpg
  43. ↑ c:File:EF DI28 (TS).jpg
  44. ↑ Wind Science and Engineering Center. (2006). A recommendation for an enhanced Fujita scale (EF-scale). Retrieved from National Weather Service Storm Prediction Center website https://www.spc.noaa.gov
  45. ↑ Doswell, Charles A.; Brooks, Harold E.; Dotzek, Nikolai (July 2009). "On the Implementation of the Enhanced Fujita Scale in the USA" (PDF). Atmospheric Research. 93 (1–3): 556–557. Bibcode:2009AtmRe..93..554D. doi:10.1016/j.atmosres.2008.11.003 . Retrieved January 20, 2020.
  46. ↑ Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. ISBN   1-879362-03-1.
  47. ↑ The Fujita Scale of Tornado Intensity Archived December 30, 2011, at the Wayback Machine at tornadoproject.com
  48. ↑ "Severe Thunderstorm Climatology". National Severe Storms Laboratory, National Oceanic and Atmospheric Administration, US Department of Commerce. March 29, 2013. Archived from the original on October 4, 2012. Retrieved May 22, 2013.
  49. ↑ "The Tornado Outbreak of March 31, 2023". National Weather Service Quad Cities. Retrieved July 21, 2023.
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