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57-484: The tornado formed 18 kilometres (11 mi) south of the city and continued for another 12 kilometres (7.5 mi) north of the city before dissipating. It was approximately 150 metres (490 ft) wide. The tornado's wind velocity has been estimated at 400 kilometres per hour (250 mph), making it the equivalent of a high-end F4 on the Fujita Scale . The tornado also displayed a multiple vortex structure throughout

114-477: A lifecycle that causes the same tornado to change in appearance over time. People in the path of a tornado should never attempt to determine its strength as it approaches. Between 1950 and 2014 in the United States, 222 people have been killed by EF1 tornadoes, and 21 have been killed by EF0 tornadoes. Around 60–70 percent of tornadoes are designated EF1 or EF0, also known as "weak" tornadoes. But "weak"

171-522: 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

228-573: A fatality) in the U.S. back to 1880. The Fujita scale was adopted in most areas outside of the United Kingdom . On February 1, 2007, the Fujita scale was decommissioned, and the Enhanced Fujita Scale was introduced in the United States. The new scale more accurately matches wind speeds to the severity of damage caused by the tornado. Though each damage level is associated with a wind speed,

285-403: A means to differentiate tornado intensity and path area, assigned wind speeds to damage that were, at best, educated guesses. Fujita and others recognized this immediately and intensive engineering analysis was conducted through the rest of the 1970s. This research, as well as subsequent research, showed that tornado wind speeds required to inflict the described damage were actually much lower than

342-497: A tornado rated F4 based on damage with a path length of 63 miles (101 km) and a path width of 800 yards (730 m) would be rated F,P,P 4,4,4. Use of the Pearson scales was not widespread, however, and it remained more common to simply list a tornado's path length and path width directly. For purposes such as tornado climatology studies, Fujita scale ratings may be grouped into classes. The Fujita scale, introduced in 1971 as

399-599: A total loss of the affected structure. Well-built homes are reduced to a short pile of medium-sized debris on the foundation. Homes with poor or no anchoring are swept completely away. Large, heavy vehicles, including airplanes , trains, and large trucks, can be pushed over, flipped repeatedly, or picked up and thrown. Large, healthy trees are entirely debarked and snapped off close to the ground or uprooted altogether and turned into flying projectiles. Passenger cars and similarly sized objects can be picked up and flung for considerable distances. EF4 damage can be expected to level even

456-677: Is a relative term for tornadoes, as even these can cause significant damage. F0 and F1 tornadoes are typically short-lived; since 1980, almost 75 percent of tornadoes rated weak stayed on the ground for 1 mile (1.6 km) or less. In this time, though, they can cause both damage and fatalities. EF0 (T0–T1) damage is characterized by superficial damage to structures and vegetation. Well-built structures are typically unscathed, though sometimes sustaining broken windows, with minor damage to roofs and chimneys . Billboards and large signs can be knocked down. Trees may have large branches broken off and can be uprooted if they have shallow roots. Any tornado that

513-500: 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 ( cycloidal marks), weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording

570-423: Is about 250 feet (76 m) across, and travels about one mile (1.6 km) before dissipating. However, tornado behavior is variable; these figures represent statistical probabilities only. Two tornadoes that look almost the same can produce drastically different effects. Also, two tornadoes that look very different can produce similar damage, because tornadoes form by several different mechanisms and also follow

627-688: 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. The scale was introduced in 1971 by Ted Fujita of the University of Chicago , in collaboration with Allen Pearson , head of

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684-498: Is confirmed, but causes no damage (i.e., remains in open fields) is normally rated EF0, as well, even if the tornado had winds that would give it a higher rating. Some NWS offices, however, have rated these tornadoes EFU (EF-Unknown) due to the lack of damage. EF1 (T2–T3) damage has caused significantly more fatalities than those caused by EF0 tornadoes. At this level, damage to mobile homes and other temporary structures becomes significant, and cars and other vehicles can be pushed off

741-488: 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 ( cycloidal marks) may also be analyzed to determine

798-548: The American Meteorological Society introduced the Enhanced Fujita scale , to help assign realistic wind speeds to tornado damage. The scientists specifically designed the scale so that a tornado assessed on the Fujita scale and the Enhanced Fujita scale would receive the same ranking. The EF-scale is more specific in detailing the degrees of damage on different types of structures for a given wind speed. While

855-700: The Knox-Metropolitan Church, meeting in the old Metropolitan Church. The Knox building was ultimately demolished. Boris Karloff , Jeanne Russell, Henrietta Crosman , and the Albini-Avolos are all characters in BD Miller's musical drama, "Swept Off Our Feet: Boris Karloff and the Regina Cyclone", which commemorated the 100th anniversary of the disaster and premiered as a July 2012 production of Regina Summer Stage . The novel Euphoria by Connie Gault won

912-434: The 2009 Saskatchewan Book Award for Fiction and prominently features the Regina Cyclone. A chapter of Frank Rasky's book Great Canadian Disasters (1961) is devoted to this tragedy. 50°26′53″N 104°36′53″W  /  50.4480°N 104.61461°W  / 50.4480; -104.61461 Fujita Scale The Fujita scale ( F-Scale ; / f u ˈ dʒ iː t ə / ), or Fujita–Pearson scale ( FPP scale ),

969-603: The EF scale wind speeds, but these are biased to United States construction practices. The EF scale also improved damage parameter descriptions. The original scale as derived by Fujita was a theoretical 13-level scale (F0–F12) designed to smoothly connect the Beaufort scale and the Mach number scale. F1 corresponds to the twelfth level of the Beaufort scale, and F12 corresponds to Mach number 1.0. F0

1026-523: The F-scale goes from F0 to F12 in theory, the EF-scale is capped at EF5, which is defined as "winds ≥200 miles per hour (320 km/h)". In the United States, the Enhanced Fujita scale went into effect on February 2, 2007, for tornado damage assessments and the Fujita scale is no longer used. The first observation confirming that F5 winds could occur happened on April 26, 1991. A tornado near Red Rock, Oklahoma ,

1083-476: The F-scale indicated, particularly for the upper categories. Also, although the scale gave general descriptions of damage a tornado could cause, it gave little leeway for strength of construction and other factors that might cause a building to sustain more damage at lower wind speeds. Fujita tried to address these problems somewhat in 1992 with the Modified Fujita Scale, but by then he was semi-retired and

1140-592: The F5 range, confirming that tornadoes were capable of violent winds found nowhere else on earth. Eight years later, during the 1999 Oklahoma tornado outbreak of May 3, another scientific team was monitoring an exceptionally violent tornado (one which eventually killed 36 people in the Oklahoma City metropolitan area ). Around 7 p.m., they recorded one measurement of 301 ± 20 miles per hour (484 ± 32 km/h), 50 miles per hour (80 km/h) faster than

1197-402: The Fujita scale is effectively a damage scale, and the wind speeds associated with the damage listed are not rigorously verified. The Enhanced Fujita Scale was formulated due to research that suggested that the wind speeds required to inflict damage by intense tornadoes on the Fujita scale are greatly overestimated. A process of expert elicitation with top engineers and meteorologists resulted in

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1254-828: The National Severe Storms Forecast Center/NSSFC (currently the Storm Prediction Center /SPC). The scale was updated in 1973, taking into account path length and width. In the United States, starting in the late 1970s, tornadoes were rated soon after occurrence. The Fujita scale was applied retroactively to tornadoes reported between 1950 and the adoption of the scale in the National Oceanic and Atmospheric Administration (NOAA) National Tornado Database. Fujita rated tornadoes from 1916 to 1992 and Tom Grazulis of The Tornado Project retroactively rated all known significant tornadoes (F2–F5 or causing

1311-704: The National Weather Service was not in a position to update to an entirely new scale, so it went largely unenacted. In the United States, on February 1, 2007, the Fujita scale was decommissioned in favor of what scientists believe is a more accurate Enhanced Fujita Scale. The meteorologists and engineers who designed the EF Scale believe it improves on the F-scale on many counts. It accounts for different degrees of damage that occur with different types of structures, both manmade and natural. The expanded and refined damage indicators and degrees of damage standardize what

1368-527: The United States and Canada. F5 and EF5 tornadoes are rare. In the United States, they typically only occur once every few years, and account for approximately 0.1 percent of confirmed tornadoes. An F5 tornado was reported in Elie, Manitoba , in Canada, on June 22, 2007. Before that, the last confirmed F5 was the 1999 Bridge Creek–Moore tornado , which killed 36 people on May 3, 1999. Nine EF5 tornadoes have occurred in

1425-528: The United States, in Greensburg, Kansas , on May 4, 2007; Parkersburg, Iowa , on May 25, 2008; Smithville, Mississippi , Philadelphia, Mississippi , Hackleburg, Alabama , and Rainsville, Alabama , (four separate tornadoes) on April 27, 2011; Joplin, Missouri , on May 22, 2011, and El Reno, Oklahoma , on May 24, 2011. On May 20, 2013, a confirmed EF5 tornado again struck Moore, Oklahoma. A typical tornado has winds of 110 miles per hour (180 km/h) or less,

1482-538: The actual wind speeds needed to cause that damage are unknown." Since then, the Enhanced Fujita Scale has been created using better wind estimates by engineers and meteorologists. The six categories are listed here, in order of increasing intensity. In 1973, Allen Pearson added additional path length and path width parameters to the Fujita scale. Under this version, each tornado would be assigned one Fujita scale rating and two Pearson scale ratings. For example,

1539-448: The air before obliterating them, flinging the wreckage for miles, and sweeping the foundation clean. Large, steel-reinforced structures such as schools are completely leveled. Tornadoes of this intensity tend to shred and scour low-lying grass and vegetation from the ground. Very little recognizable structural debris is generated by EF5 damage, with most materials reduced to a coarse mix of small, granular particles and dispersed evenly across

1596-411: The center of tornadoes, no measurements confirm it. A few home barometers had survived close passes by tornadoes, recording values as low as 24 inches of mercury (810 hectopascals), but these measurements were highly uncertain. In 2003, a U.S. research team succeeded in dropping devices called "turtles" into an F4 tornado, and one measured a pressure drop of more than 100 hectopascals (3.0 inHg) as

1653-497: The city's residential areas, leaving individual houses untouched next to homes that were completely flattened. The tornado hit Regina at approximately 5:00 p.m. on June 30, 1912. The tornado formed 18 km south of the city and was roughly 150 metres wide by the time it reached Regina. The worst damage was in the residential area north of Wascana Lake and the central business district. Many buildings, both brick and wood, were entirely destroyed. "The new Central Library building

1710-447: The damage described at each category. The error manifests itself to an increasing degree as the category increases, especially in the range of F3 through F5. NOAA notes that "precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar-looking damage from place to place—even from building to building. Without a thorough engineering analysis of tornado damage in any event,

1767-670: The disaster to pay for the nightly use of cots set up in schools and city parks. It also required homeowners to pay for the removal of rubble from their homes. Debris was cleaned up rather quickly. "The storm damaged the Metropolitan Methodist Church, [the Knox Presbyterian Church, the First Methodist,] the library, the YWCA [and YMCA], and numerous other downtown buildings; in the warehouse district, it destroyed many of

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1824-474: The early 1970s. However, one can find accounts (e.g. [1] ; be sure to scroll down) of some remarkable work done in this field by a U.S. Army soldier, Sergeant John Park Finley . In 1971, Dr. Fujita introduced the idea of a scale to measure tornado winds. With the help of colleague Allen Pearson , he created and introduced what came to be called the Fujita scale in 1973. The F in F1, F2, etc. stands for Fujita. The scale

1881-523: The ground and tossed as projectiles. Wooded areas suffer an almost total loss of vegetation, and some tree debarking may occur. Statistically speaking, EF3 is the maximum level that allows for reasonably effective residential sheltering in place in a first-floor interior room closest to the center of the house (the most widespread tornado sheltering procedure in America for those with no basement or underground storm shelter). EF4 (T8–T9) damage typically results in

1938-593: The ground, and lighter objects can become small missiles , causing damage outside of the tornado's main path. Wooded areas have a large percentage of their trees snapped or uprooted. EF3 (T6–T7) damage is a serious risk to life and limb and the point at which a tornado statistically becomes significantly more destructive and deadly. Few parts of affected buildings are left standing; well-built structures lose all outer and some inner walls. Unanchored homes are swept away, and homes with poor anchoring may collapse entirely. Small vehicles and similarly sized objects are lifted off

1995-447: The higher intensity is from subvortices . In the United States, 80% of tornadoes are rated EF0 or EF1 (equivalent to T0 through T3). The rate of occurrence drops off quickly with increasing strength; less than 1% are rated as violent (EF4 or EF5, equivalent to T8 through T11). For many years, before the advent of Doppler radar, scientists relied on educated guesses for tornado wind speed. The only evidence indicating wind speeds found in

2052-409: The intensity and assign a rating. Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer-track (and longer-lived) tornadoes tend to be stronger. In the case of violent tornadoes, only a small portion of the path area is of violent intensity; most of

2109-488: The most robustly built homes, making the common practice of sheltering in an interior room on the ground floor of a residence insufficient to ensure survival. A storm shelter, bomb shelter, reinforced basement, or other subterranean shelter can provide substantial safety against EF4 tornadoes. EF5 (T10–T11) damage represents the upper limit of tornado power, and destruction is almost always total. An EF5 tornado pulls well-built, well-anchored homes off their foundations and into

2166-525: The previous record. Though this reading is just short of the theoretical F6 rating, the measurement was taken more than 100 feet (30 meters) in the air, where winds are typically stronger than at the surface. In rating tornadoes, only surface wind speeds or the wind speeds indicated by the damage resulting from the tornado, are taken into account. Also, in practice, the F6 rating is not used. While scientists have long theorized that extremely low pressures might occur in

2223-575: The rating of F6, but both were later downgraded to F5. Based on aerial photographs of the damage it caused, Fujita assigned the strongest tornado of the 1974 Super Outbreak , which affected Xenia, Ohio, a preliminary rating of F6 intensity ± 1 scale. The 1977 Birmingham–Smithfield F5 tornado's damage was surveyed by Ted Fujita and he "toyed with the idea of rating the Smithfield tornado an F6". In 2001, tornado expert Thomas P. Grazulis stated in his book F5–F6 Tornadoes ; "In my opinion, if there ever

2280-546: The ratings. The highest tornado rated on the IF scale was the 2021 South Moravia tornado , which was rated an IF4. In the U.S., F0 and F1 (T0 through T3) tornadoes account for 80% of all tornadoes. The rate of occurrence drops off quickly with increasing strength—violent tornadoes (F4/T8 or stronger), account for less than one percent of all tornado reports. Worldwide, strong tornadoes account for an even smaller percentage of total tornadoes. Violent tornadoes are extremely rare outside of

2337-507: The road or flipped. Permanent structures can suffer major damage to their roofs. EF2 (T4–T5) tornadoes are the lower end of "significant" yet are stronger than most tropical cyclones (though tropical cyclones affect a much larger area and their winds take place for much longer duration). Well-built structures can suffer serious damage, including roof loss, and the collapse of some exterior walls may occur in poorly built structures. Mobile homes, however, are destroyed. Vehicles can be lifted off

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2394-479: The storage buildings. Damage from the tornado is estimated to be F4 on the Fujita scale . The tornado killed 28 people, injured hundreds, and left 2,500 people homeless, out of a population of about 30,213 (in 1911). Around 500 buildings were destroyed or damaged. Property damage was quantified at $ 1.2 million CAD, and it would be forty years before the $ 4.5 million CAD private and public debt incurred to rebuild and repair

2451-458: The tiny spring runoff Wascana Creek, which only flowed in early spring. "The cyclone claimed twenty-eight lives and was the worst in Canadian history in terms of deaths. It also rendered 2,500 persons temporarily homeless, and caused over $ 1,200,000 in property damage. It took the city two years to repair the damage and ten years to pay off its storm debt." The city forced those rendered homeless by

2508-593: The tornado passed directly overhead. Still, tornadoes are widely varied, so meteorologists are still researching to determine if these values are typical or not. In 2018, the International Fujita scale was created by the European Severe Storms Laboratory as well as other various European meteorological agencies. Unlike the other three scales (Fujita, Enhanced Fujita, and TORRO), the International Fujita scale has overlapping wind speeds within

2565-435: The tornado was the damage left behind by tornadoes that struck populated areas. Some believed they reach 400 miles per hour (640 kilometers per hour); others thought they might exceed 500 miles per hour (800 km/h), and perhaps even be supersonic . One can still find these incorrect guesses in some old (until the 1960s) literature, such as the original Fujita intensity scale developed by Dr. Tetsuya Theodore "Ted" Fujita in

2622-550: The tornado's damage path. Large, multiple-ton steel frame vehicles and farm equipment are often mangled beyond recognition and tossed miles away or reduced entirely to unrecognizable parts. The official description of this damage highlights the extreme nature of the destruction, noting that "incredible phenomena will occur"; historically, this has included such displays of power as twisting skyscrapers , ripping roofs off of tornado bunkers , leveling entire communities , and stripping asphalt from roadbeds . Despite their relative rarity,

2679-578: The usefulness of the TORRO scale over the Fujita scale—while it may be helpful for statistical purposes to have more levels of tornado strength, often the damage caused could be created by a large range of winds, rendering it hard to narrow the tornado down to a single TORRO scale category. Research conducted in the late 1980s and 1990s suggested that even with the implication of the Fujita scale, tornado winds were notoriously overestimated, especially in significant and violent tornadoes. Because of this, in 2006,

2736-425: The warehouse district, it destroyed many of the storage buildings. The CPR Roundhouse was stripped to the rafters, and boxcars were pulled from the tracks and hurtled into the air." Such damage was especially appalling to see as well as experience since Regina had been built on an entirely featureless plain, lacking any trees or vegetation other than natural wild prairie grass and without any hills or rivers apart from

2793-471: Was an F6 tornado caught on video, it was the Pampa, Texas tornado of 1995 ". In 2023, it was announced by the Storm Prediction Center and National Weather Service Norman, Oklahoma that the 1970 Lubbock tornado was originally rated F6, which was later downgraded to its official rating of F5. Furthermore, the original wind speed numbers have since been found to be higher than the actual speeds required to incur

2850-553: Was available on damage caused by wind, so the original scale presented little more than educated guesses at wind speed ranges for specific tiers of damage. Fujita intended that only F0–F5 be used in practice, as this covered all possible levels of damage to frame homes as well as the expected estimated bounds of wind speeds. He did, however, add a description for F6, which he called an "inconceivable tornado", to allow for wind speeds exceeding F5 and possible advancements in damage analysis that might show it. In total, two tornadoes received

2907-456: Was based on a relationship between the Beaufort scale and the Mach number scale; the low end of F1 on his scale corresponds to the low end of B12 on the Beaufort scale, and the low end of F12 corresponds to the speed of sound at sea level, or Mach 1. In practice, tornadoes are only assigned categories F0 through F5. The TORRO scale, created by the Tornado and Storm Research Organization (TORRO) ,

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2964-425: Was developed in 1974 and published a year later. The TORRO scale has 12 levels, which cover a broader range with tighter graduations. It ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. T0–T1 roughly corresponds to F0, T2–T3 to F1, and so on. While T10–T11 would be roughly equivalent to F5, the highest tornado rated to date on the TORRO scale was a T8. Some debate exists as to

3021-411: Was monitored by scientists using a portable Doppler weather radar , an experimental radar device that measures wind speed. Near the tornado's peak intensity, they recorded a wind speed of 115–120 meters per second (260–270 miles per hour; 410–430 kilometers per hour). Though the portable radar had the uncertainty of ±5–10 metres per second (11–22 mph; 18–36 km/h), this reading was probably within

3078-484: Was opened May 11, 1912, and just six weeks later, the new library was among the many buildings that suffered damage." "In just twenty minutes it completely leveled a number of houses, and caused other houses to explode as the pressure inside the structures rose when the tornado passed overhead." The affluent residential area to the south was substantially diminished, but the tornado left houses untouched here and there immediately adjacent to houses which were flattened. "[I]n

3135-410: Was placed at a position specifying no damage (approximately the eighth level of the Beaufort scale), in analogy to how Beaufort's zeroth level specifies little to no wind. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes. At the time Fujita derived the scale, little information

3192-488: Was repaid. The only remaining "souvenir" of this event is different-coloured bricks on the north wall of Regina's Knox-Metropolitan United Church (the former Metropolitan Methodist church). The bricks show where the wall was rebuilt after its tornado-caused collapse. Knox Presbyterian, Metropolitan Methodist and First Baptist, all being brick, were rebuilt after the tornado. Knox and Metropolitan both became United Church in 1925, and merged their congregations in 1951 to become

3249-449: Was somewhat ambiguous. It also is thought to provide much better estimates of wind speeds and sets no upper limit on the wind speeds for the highest level, EF5. Environment Canada began using the Enhanced Fujita scale in Canada on April 1, 2013. The U.S. and Canada are the only countries to officially adopt the Enhanced Fujita scale. Tornado intensity Tornado intensity is the measure of wind speeds and potential risk produced by

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