Fascinating and Accurate Tornado Records – the Deadliest, the Fastest, the Rarest

Several EF5 tornadoes have thrown industrial equipment weighing in excess of 15,000 lbs long distances. At top left, the 2011 El Reno tornado hurled an oil tanker weighing approximately 25,000 lbs a mile without leaving any noticeable ground impacts. At top right, the 1970 Lubbock tornado tossed a 26,000 lb fertilizer tank 3/4 of a mile over a freeway and several undamaged fences. At bottom left, the 2011 Tuscaloosa tornado hurled a train car weighing 71,600lbs 130 yards in one throw, according to witnesses. At bottom right, the 1995 Pampa tornado lifted a 35,000 lb lathe.

Several EF5 tornadoes have thrown industrial equipment weighing in excess of 15,000 lbs long distances. At top left, the 2011 El Reno tornado hurled an oil tanker weighing approximately 25,000 lbs a mile without leaving any noticeable ground impacts. At top right, the 1970 Lubbock tornado tossed a 26,000 lb fertilizer tank 3/4 of a mile over a freeway and several undamaged fences. At bottom left, the 2011 Tuscaloosa tornado hurled a train car weighing 71,600lbs 130 yards in one throw, according to witnesses. At bottom right, the 1995 Pampa tornado lifted a 35,000 lb lathe.

□ Accurate tornado statistics can be difficult to find. Recording techniques were not standardized before the weather radar age, so information on tornadoes that occurred before 1970 is often unreliable. Furthermore, lists of the deadliest and longest tracked tornadoes in world history are easy to find and dominated by 19th and early-20th century events.

To level the playing field and promote the dissemination of credible information, all of the following records cover tornadoes that occurred after 1970. Click each link in the index below to jump to a specific section. This page will undoubtably go through several edits and expand as more notable tornado records are uncovered. 

I. The Deadliest Tornadoes on Record

II. The Longest Tornado Damage Paths

III. The Fastest Tornadoes Ever Recorded

IV. Violent or Unusual Tornado Records

-IVa. The Highest Altitude Violent Tornado

-IVb. The Deadliest and Most Intense Anticyclonic Tornado Ever Recorded

-IVc. The Deadliest Hurricane Spawned Tornado

-IVd. The Highest Tornado Fatality Rate

-IVe. The Most Fatalities in a Single Building

-IVf. The Most Fatalities in a Single Mobile Home Park

-IVg. The Fastest Tornado Movement Ever Recorded Using Photogrammetry

-IVh. The Heaviest Object Ever Lifted by a Tornado

V. Graphs

Va. Graph of Tornadoes Causing 10+ and 20+ Fatalities by Decade

Vb. Graph of the Deadliest Tornadoes by Decade

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I.
□ The Deadliest Tornadoes on Record

The 2011 Joplin tornado is by far the deadliest tornado of the past 50 years. Considering the storm's incredible intensity and size, it is remarkable the number of deaths did not surpass 200. All three of the deadliest tornadoes since 1970 occurred during the 2011 tornado season, the worst in modern history.

The 2011 Joplin tornado was by far the deadliest tornado of the past 50 years. Considering the storm’s incredible intensity and size, it is remarkable the number of deaths did not surpass 200. All three of the deadliest tornadoes since 1970 occurred during the 2011 tornado season, the worst in modern history.

1. 158 fatalities – Joplin, Missouri – May 22, 2011

□ A violent EF5 tornado rapidly intensified as it entered heavily populated sections of Joplin. The storm holds the post-1970 record for the most fatalities in frame homes (approximately 70) and the most fatalities in commercial buildings (approximately 20). The commercial deaths do not include the large number of fatalities at medical facilities, churches and private organizations.

2. 72 fatalities – Hackleburg/Phil Campbell, Alabama – April 27, 2011

One of the most impressive tornadic events in history carved a 132-mile path of devastation through largely rural areas of northern Alabama. The EF5 tornado had an exceptionally high fatality to injury ratio. The storm holds the post-1970 record for the longest swath of EF5 damage (including approximately 40 consecutive miles at EF5 intensity).

3. 64 fatalities – Tuscaloosa/Concord, Alabama – April 27, 2011

□ Borderline EF5 tornado caused more than 40 deaths in Tuscaloosa. Extremely well-covered by local news agencies and photographers. Caused high-end EF4 damage from Tuscaloosa to the suburbs of Birmingham.

4. ≈47 fatalities – Pugh City, Mississippi – February 21, 1971

□ A fast-moving F4 tornado nearly wiped out the town of Pugh City, killing 22 residents. Dozens of small homes were swept completely away. Official death toll of 58 is likely the result of a tornado family.

5. 42 fatalities – Wichita Falls, Texas – April 10, 1979

□ A large tornado left a wide swath of marginal F4 damage in Wichita Falls. The historic storm holds the post-1970 record for the greatest number of fatalities in vehicles (25). The majority of the deaths in automobiles were people attempting to flee the storm.

6. ≈41 fatalities – Inverness, Mississippi – February 21, 1971

□ A fast-moving F5 tornado passed directly through the town of Inverness, killing approximately 20 residents. Most of the deaths were in poorly built homes that were obliterated.

7. 36 fatalities – Bridge Creek/Moore, Oklahoma – May 3, 1999

□ Violent F5 tornado killed 13 people in rural areas while at maximum intensity. The storm then caused another 23 deaths as it tracked through the Oklahoma City suburbs. Holds record for the highest doppler velocity ever measured – approximately 302mph.

8a. 32 fatalities – Oak Grove, Alabama – April 8, 1998

□ Marginal F5 tornado caused a high number of fatalities as it chewed through small towns near Birmingham after dark. The worst damage was confined to several small streaks of intense devastation.

8b. 32 fatalities – Xenia, Ohio – April 3, 1974

□ Infamous multi-vortex tornado became the deadliest and most damaging single storm in the 1974 Super Outbreak. Brief film of the tornado captured by a high school student was broadcast on news networks across the world.

9. 31 fatalities – Brandenburg, Kentucky – April 3, 1974

□ Violent F5 tornado swept away well-constructed houses in the town of Brandenburg. The storm struck far fewer homes than the Xenia tornado yet caused a similar death toll due to its extreme intensity.

10. 30 fatalities – Saragosa, Texas – May 22, 1987

Short lived multi-vortex tornado touched down and rapidly intensified as it passed over a small town in southwest Texas. Most of the fatalities occurred in the destruction of a crowded church.

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II.
□ The Longest Tornado Damage Paths

-Due to the high number of tornado families that have been officially recorded as a single storm, an accurate list is difficult to compile. Tornadoes thought to have been two or more separate storms are not included. This list will undoubtably go through various edits.

The longest tracked tornadoes generally occur in the South in the spring and fall. At left, one of the longest tracked tornadoes in history caused EF5 damage in Hackleburg. At right, an power tornado probably capable of causing F5 damage killed four people in the obliterated home at bottom. One of the bodies was found in a tree a quarter mile from the foundation (Grazulis, 1995).

The longest tracked tornadoes generally occur in the South in the spring and fall when upper-level winds are more conductive to rapid forward movement. At left, one of the longest tracked tornadoes in history caused EF5 damage in Hackleburg. At right, an extremely long-lived nighttime tornado killed four people in the obliterated home at bottom near Jackson, Mississippi, in 1992. The body of one of the occupants was found in a tree a quarter mile from the foundation (Grazulis, 1997).

1. 149 miles – Yazoo City, Mississippi – April 24, 2010

□ A large, often obscured tornado sped through central Mississippi, killing 10 people in and near Yazoo City. The majority of the damage path was through sparsely populated forestland.

2. 132 miles – Hackleburg/Phil Campbell, Alabama to TN – April 27, 2011

Violent EF5 tornado travelled across nearly all of northern Alabama, causing 72 deaths before crossing the Tennessee border and continuing for an additional ten miles through Franklin County. The storm left strong tornado damage (EF3+) over more than 110 miles (NWS Survey).

3a. 128 miles – Brandon, Mississippi – November 21, 1992

□ Violent, rain-wrapped tornado killed 12 near Jackson around midnight. Four of the deaths occurred when a large, two-story brick home in the Easthaven subdivision was completely destroyed.

3b. 128 miles – Cordova, Alabama – April 27, 2011

□ Fast-moving tornado killed 13 people in Alabama. While officially rated an EF4, the tornado left severe ground scouring in unpopulated areas and hurled a vehicle nearly one mile.

4. 124 miles – Raleigh, Mississippi to AL – April 27, 2011

□ A Lesser know violent tornado during the 2011 Super Outbreak killed 7 in Mississippi and Alabama. Formed farther south than most of the tornadoes on April 27 and left a quarter-mile wide swath of fallen trees through a forest reserve.

5. 122 miles – Clinton, Arkansas – February 5, 2008

□ A fast-moving and long duration EF4 tornado ripped through largely rural areas of Arkansas. The 13 fatalities were spread out over a 30 mile area beginning in Pope County.

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III.
□ The Fastest Tornadoes Ever Recorded

-Due to their rapidly shifting nature, it is difficult to ascertain the forward speed of a tornado over a specified time period. Decaying tornadoes can momentarily exceed 90mph, but these great speeds are never maintained. Most of the fastest tornadoes occur in the South from late-November through April, but similar conditions can cause extremely fast moving tornadoes from Tennessee to Michigan.

In 2012, an extremely violent and fast-moving tornado was filmed as it sped through the town of Henryville, Indiana, at more than 60mph (Video contains strong language). The multi-vortex tornado was powerful enough to loft vehicles more than 200 yards, scour a highway of pavement and completely sweep away several large, two-story brick homes. While rated an EF4 by the NWS, the tornado probably had instantaneous gusts capable of causing EF5 damage in areas east of Henryville. (Video by Rhett Adams)

1a. 70mph+ – April 27, 2011

Many of the tornadoes in the 2011 Super Outbreak reached speeds of 70mph at some point in their development. Examples include the Hackleburg/Phil Campbell tornado as it ripped through Marion and Franklin Counties and the Smithville, Mississippi, tornado as it caused some of the most intense EF5 damage ever photographed in Monroe County.

1b. 70mph+ – March 2, 2012

The deadliest tornado outbreak of 2012 brought violent and fast-moving tornadoes to the states of Indiana and Kentucky. The deadliest two tornadoes in the outbreak – the Henryville, Indiana, tornado and the West Liberty, Kentucky, tornado – may have approached 75mph in periods of their development.

1c. 70mph+ – April 3, 1974

During the 1974 Super Outbreak, nearly every supercell was moving in excess of 50mph. The violent tornadoes that occurred in the state of Alabama – including the infamous Guin tornado – may have reached or momentarily surpassed 75mph.

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IV.
□ Violent or Unusual Tornado Records

IVa. The Highest Altitude Violent Tornado

One of the most unusual violent tornadoes in recorded history touched down high in the mountains near Yellowstone National Park. The rain-wrapped tornado was imbedded within an exceptionally violent mesocyclone with large hail and frequent microbursts. Fujita toured the nearly mile wide damage swath and noted extreme tree damage consistent with violent (F4/F5) tornadic winds. The tornado proved that the deadliest tornado in United States history, theoretically, could strike a place as unexpected as

One of the most unusual tornadoes in recorded history touched down high in the mountains near Yellowstone National Park on July 21, 1987. The rain-wrapped tornado, which travelled at nearly 60mph, was imbedded within an exceptionally violent mesocyclone that contained large hail and frequent microbursts. Fujita toured the 1.5 mile wide damage swath and noted bursts of extreme tree damage consistent with violent (F4/F5) tornadic winds more than 9,000ft above sea level (the worst damage is visible as the lighter area on the hillside just above center). Some mountain peaks affected by the storm were at an altitude of nearly 11,000ft (Fujita, 1989). The rare storm, which was likely capable of causing a wide swath of EF2, EF3 and EF4 damage early in its life, proved that potentially catastrophic tornadoes can occur well-outside “tornado alley.” Had the storm impacted a large population center, it could have caused damage and loss of life comparable to the 2011 Joplin tornado.

IVb. The Deadliest and Most Intense Anticyclonic Tornado Ever Recorded

The West Bend tornado left a narrow swath of F4 damage through a housing subdivision in town.

In April of 1981, a thunderstorm developed over Washington County, Wisconsin. The storm resembled a typical nighttime thunderstorm on weather radar, so no tornado watch was issued. Despite the storm’s modest size and low cloud tops, it spawned an unusual anticyclonic tornado just after midnight. The short-lived tornado touched down at the edge of a neighborhood in the town of West Bend (visible above) and immediately began causing F4 damage (Wakimoto, 1983). Several two-story houses were leveled to the ground and three people were killed, including one man who was thrown more than 50 yards from his destroyed home. The rapidly intensifying tornado was exceptionally narrow, often less than 50 yards in width, and dissipated after traveling less than two miles. The event remains a meteorological oddity and the only violent anticyclonic tornado ever recorded. (Images by Patrick Golembiewski)

IVc. The Deadliest Hurricane Spawned Tornado 

In 1964, Hurricane Hilda made landfall in Louisiana as a weakening category 3 storm. Before the hurricane's eye reached the coast, a violent tornado was spawned in the swampland 30 miles south of New Orleans. The F4 tornado travelled westward over a narrow strip of homes and buildings that lined a waterway, killing 22 residents.

In October of 1964, Hurricane Hilda made landfall in Louisiana as a weakening Category 3 storm. Before the hurricane’s eye reached the coast, a violent tornado was spawned 30 miles south of New Orleans in a marshy area near the Gulf of Mexico. The F4 tornado travelled westward over a narrow strip of homes and buildings that lined a waterway in the town of Larose, killing 22 residents. Some homes were swept completely away and many of the bodies were carried more than 100 yards and later recovered in a nearby bayou. The storm remains the deadliest hurricane spawned tornado in US history and one of the strongest such storms ever recorded.

IVd. The Highest Above-Ground Tornado Fatality Rate

On Ma7 27, 1997, perhaps the most violent tornado in modern history swept through two clusters of homes just outside Jarrell, Texas. The slow-moving F5 tornado completely swept away two dozen homes and ground the remains into tiny pieces. Within the streak of worst damage, which expanded over a quarter-mile in width, there were no survivors above ground. The only people to that didn't loose their lives were crowded in an underground storm cellar on Double Creek Drive, where most of the fatalities occurred.

On May 27, 1997, perhaps the most violent tornado in modern history passed over two clusters of homes just outside Jarrell, Texas. The slow-moving F5 tornado completely swept away two dozen homes and ground the debris into tiny pieces. Within the streak of worst damage, which expanded over a quarter-mile in width, there were no survivors above ground. All of the vegetation in the worst affected areas was scoured from the ground, leaving nothing but empty foundations and fields of mud.

IVe. The Most Fatalities in a Single Building (post-1970)

At left, the 1987 Saragosa, Texas, tornado killed 22 people in the Guadelupe Church during a graduation ceremony for young students. At center, the 1994 Piedmont, Alabama, tornado killed 20 people at the Goshen United Methodist Church during Palm Sunday services. At right, the 2011 Joplin tornado leveled and partially swept away the Greenbriar Nursing Home. Of the approximately 90 residents and nurses in the building, 21 died.

At left, the 1987 Saragosa, Texas, tornado killed 22 people in the Guadelupe Church during a graduation ceremony for young students. At center, the 1994 Piedmont, Alabama, tornado killed 20 parishioners at the Goshen United Methodist Church during Palm Sunday services (Survey Report). At right, the 2011 Joplin tornado leveled and partially swept away the Greenbriar Nursing Home. Of the approximately 90 residents and nurses in the building, 21 died.

IVf. The Most Fatalities in a Single Mobile Home Park

In November of 2005, a fast moving nighttime tornado touched down near Evasnville, Indiana. Around 2am, the tornado struck the Eastbrook Mobile Home Park while residents were asleep. In the park alone, 20 people were killed as mobile homes were swept completely away along the southern edge of the park.

In November of 2005, a fast-moving nighttime tornado touched down near Evasnville, Indiana. Around 2am, the multi-vortex tornado struck the Eastbrook Mobile Home Park while most of the area’s residents were asleep. A total of 20 people were killed as the F3 tornado swept away mobile homes along the southern edge of the park. The event remains the deadliest tornado disaster in a mobile home park. In July of 1987, one of Canada’s deadliest tornadoes killed 15 people in the Evergreen Mobile Home Park in Edmonton, Alberta.

IVg. The Fastest Tornado Movement Ever Recorded Using Photogrammetry

Photogrammetry is a technique that allows for the measurement of debris movement in the visible portions of tornadoes. The highest officially calculated velocity using Fujita's meticulous techniques was 284mph in the 1974 Parkersburg, Indiana, tornado. The official analysis program ended in the 80's, but rough calculations by Tom Grazulis indicated particle motions of 300mph just above ground level in the 1995 Pampa, Texas, tornado.

Photogrammetry is a technique that allows for the measurement of debris movement in the visible portions of tornadoes. The highest officially calculated velocity using Fujita’s meticulous techniques was 284mph in the 1974 Parker City, Indiana, tornado (Forbes, Bluestein, 2001). The official analysis program ended in the 80’s, but rough calculations by Tom Grazulis indicated particle motions of 300mph just above ground-level in the 1995 Pampa, Texas, tornado (two vehicles are visible mid-air left of the funnel). Basic photogrammetry techniques indicate the 2007 Elie, Manitoba, tornado was of similar intensity (a van being thrown 200 yards from the tornado is visible at right).

IVh. The Heaviest Object Ever Lifted by a Tornado

In June of 1990, an exceptionally violent tornado formed in the desert-land of southwest Texas. Near the end of the tornado's path, an oil production facility was destroyed (at left) and three oil tanks weighing 180,000lbs were moved three miles to the east. Two of the tanks were found 600ft up a hillside with a 40 degree incline. This is one of the most impresive instances of tornado damage ever recorded and perhaps the only instance of an object over 100,000lbs being moved a great distance.

In June of 1990, an exceptionally violent tornado formed in the desert-land of southwest Texas. Near the end of the tornado’s path in Bakersfield Valley, a production facility was destroyed (at left) and three oil tanks weighing 180,000lbs were moved three miles to the east. Two of the tanks were found 600ft up a hillside with a 40 degree incline. This is one of the most impresive instances of tornado damage ever recorded and perhaps the only documented instance of an object over 100,000 lbs being moved a long distance. (Images by Wayne Greene)

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V.
□ Va. Graph of Tornadoes Causing 10+ Deaths by Decade

Since the the 70's, the average amount of lead-time preceding a tornado has not changed significantly. As a result, the number of overall fatalities bottomed out in the last two decades of the 20th century.

Since the the 70’s, the average amount of lead-time preceding a tornado has not changed significantly. As a result, the trend towards fewer fatalities has bottomed out. Urban sprawl and the increasing population in many severe weather-prone states will likely lead to an upturn in tornadoes causing 10 or more fatalities in the coming decades. Due to the random nature of all weather disasters, there is extreme variance in the number of deaths per year. Using a statistical bell curve of all tornado fatalities from 1980 to 2010, the 2011 tornado season’s death toll would have been expected less than once in a million years. In reality, a deadlier season is likely in the next century.

□ Vb. Graph of the Deadliest Tornadoes by Decade

No single tornado caused more than 50 deaths between 1955 and 2011. After several widely visible and well-covered tornadoes (Xenia '74, Wichita Falls '79, Bridge Creek '99) failed to cause more than 100 deaths, it was considered by some an "impossibility" in the weather-radar age. In truth, major cities and crowded freeways open the possibility to a single storm causing more than 1,000 deaths.

No single tornado caused more than 50 deaths between 1955 and 2011. After several widely visible and well-covered tornadoes (Xenia ’74, Wichita Falls ’79, Bridge Creek ’99) failed to cause more than 100 fatalities, it was considered by some an “impossibility” in the weather-radar age. In truth, major cities and crowded freeways open the possibility to a single storm causing more than 1,000 deaths.

The Highest Winds Ever Measured by Mobile Doppler Radar in Five Violent Tornadoes

“In small, intense tornadoes, and especially in multiple vortices, radar observations of debris may be severely underestimating air motions.” – The Center for Severe Weather Research

Image of the violent Spencer, South Dakota, tornado of 1998. Winds over 260 mph were recorded as the tornado obliterated 100 homes and killed six people. (StormStock)

□ Mobile doppler radar remains the only quantitative and practical technology able to analyze tornadic winds. Direct observations in winds over 200mph are next to impossible, so doppler radar allows scientists the opportunity to – from a safe distance – see behind the curtain of dirt and debris. It is important to understand, however, that doppler devices do not actually “measure” anything. Instead, they analyze the motion of debris particles within tornadoes and provide a statistical range from which tornadic wind speeds can be estimated.

Despite over two decades of active use, only a handful of violent tornadoes have ever been documented at close range. Of the tornadoes that have been tracked, only a fraction of their total path lengths were thoroughly analyzed. So doppler velocities, while useful, are by no means an objective measurement that can be used to compare or categorize individual storms.

Image of the Bridge Creek tornado from the Doppler On Wheels (DOW) right as the record 300 mph+ velocity was recorded. The tornado was in the process of scouring grass and pavement from the ground in Grady County. Higher winds have undoubtedly occurred in other E/F5 tornadoes.

1. The highest reading ever recorded by mobile doppler radar was during the May 3rd, 1999, Great Plains tornado outbreak. The world-record velocity was taken just before 7pm as the F5 Bridge Creek tornado roared towards the Oklahoma City metro area. Originally calibrated at 318 mph, the reading was later reduced to 301 mph +/- 20 mph (135 +/- 10 m/s). A more accurate interpretation of the data is the statistical range the DOW estimated – 280 mph to 322 mph. At two standard deviations (2% likelihood) the measurement would be 369 mph, according to the DOW website. The reading was taken at a fairly low altitude (about 95 ft above the ground) but the surface level winds may have been slightly less – probably in the 260 to 290 mph range. At the same time, recent research in powerful hurricanes has shown that surface winds, which are generally estimated to be 10 to 15% lower than flight level winds, can actually be equal to or even exceed high altitude winds in exceptionally powerful, rapidly intensifying tropical cyclones (Uhlhorn, 2012). While these observations are specific to hurricanes, the same principle may apply to powerful tornadoes undergoing a period of rapid intensification.

The DOW does not directly measure winds but instead the movement of airborn particles. No attempt has ever been made to compare DOW observations with actual ground readings in violent tornadoes for obvious reasons. The DOW team admits that their technology likely fails to account for the many small-scale vortices that exist in strong tornadoes as well as the vertical component of tornadic winds.

The Bridge Creek tornado caused extreme ground scouring across the majority of its path. (Image by Bob Webster)

Image of the F5 tornado as analyzed by the DOW. Note the hurricane-like “eye” at center. Survivor testimony and scientific data indicates tornadoes, particularly large tornadoes, have calm centers with light winds.

2. Besides the Bridge Creek event, only one other E/F5 tornado has been analyzed by mobile doppler radar. The El Reno, Oklahoma, EF5 tornado formed on May 24th, 2011, during a large scale outbreak that also produced the deadly Joplin tornado two days earlier. The tornado killed nine people and left a streak of scoured earth as it thundered through rural areas west and north of Oklahoma City. Though still not officially made public, a rapid scanning mobile radar recorded a radial velocity of  280 mph (125 m/s) about 220 ft above ground level early in the tornado’s life. The tornado was given an EF5 rating based on the doppler measurement, and its intensity is currently quoted in NWS literature as having been “greater than 210mph” at ground level. The mobile radar team was only able to follow the tornado for part of its 65-mile long path, so it is very possible the tornado had higher winds in later stages of its life.

The El Reno tornado had a significantly longer path than the Bridge Creek tornado and may also have been more intense, though such comparison is purely speculation. The tornado became rain wrapped minutes after touching down and was obscured for much of its life. The fatality rate (the number of fatalities divided by the total number of people in the tornado’s path) in the El Reno/Piedmont tornado was significantly higher than the Bridge Creek tornado.

Severe tree and vehicle damage from the EF5 El Reno tornado. During the May 2011 tornado outbreak in Oklahoma, there were several other tornadoes that likely reached EF5 intensity. The Chickasha tornado formed one hour after the El Reno tornado and was well-documented by storm chasers. It scoured grass and pavement from the ground and likely had winds well into the EF5 range. (Image by Jim LaDue)

Video still of the El Reno tornado. For much of its life the EF5 tornado was a mile wide and obscurred by precipitation. (Image by JeopardyTempest)

3. The Red Rock, Oklahoma tornado on April 26th, 1991 was part of a larger outbreak that also caused the infamous Andover, Kansas F5 tornado. Of all the violent tornadoes that day, the Red Rock tornado was likely the most intense. It had the most impressive radar presentation and the longest damage path. The tornado hit very little as it roared through sparsely populated countryside and was only given an F4 rating as a result. A team headed by Howard Bluestein recorded a velocity of 268 mph in the tornado’s mature stage. This was the highest reading ever recorded using mobile doppler technology up until the Bridge Creek tornado eight years later. The Red Rock measurement was taken about 550 ft above the ground. Like most of the tornadoes tracked by mobile doppler radar, only a part of its life cycle was analyzed, and higher winds may have occurred in other stages of its development.

The Red Rock tornado was exceedingly violent, and video from storm chasers show it had some of the most impressive tornadic motion ever recorded.

View of the Red Rock tornado close to the time the 268 mph velocity was recorded.

4. The Spencer, South Dakota F4 tornado was followed by the DOW as it travelled generally to the east-southeast on May 30, 1998. The DOW recorded ground relative wind-speeds as high as 264 mph (118 m/s) close to the time the tornado passed through the small town of Spencer (Wurman, 2005). The measurement was taken at a fairly low altitude – 160 ft – but still well above what the NWS constitues as “ground level.” Only a tiny section of the tornado’s path crossed over man-made structures, so the tornado’s true damage potential was likely not realized. It was given an F4 rating after a damage survey was conducted, but many researchers believe the tornado had F5 potential. Six fatalities occurred in Spencer, five of them in a two story apartment building that was obliterated.

An interesting feature of the Spencer tornado was revealed when the DOW measurements were compared with a ground damage survey. The tornado was shown to have a pronounced eye, and much like a hurricane, the winds on the right side of the tornado were significantly stronger than the winds on the left side due to the addition of the tornado’s forward momentum (Wurman, 2005). The high-end F4 damage was all south of the torndo’s center whereas areas north of the eye had lighter (F1 – F2) damage. According to the DOW analysis, the worst affected areas in Spencer experienced hurricane force winds for two minutes and violent (200mph+) winds for about 20 seconds. The tornado was often obscurred by dust, but video from storm chasers show that the storm had extremely rapid rotation.

Aerial view of F4 damage in Spencer. The large building at right is where five deaths occurred.

5. The Mulhall, Oklahoma tornado occurred on the same day as the Bridge Creek tornado on May 3rd, 1999. Several researchers believe this tornado was more violent than its infamous cousin, and the DOW measurements revealed the Mulhall tornado was significantly larger. The DOW estimated a velocity of 257 mph (115 m/s) and one CSWR article mention readings of 277 mph to 299 mph in regards to this tornado. The veracity and context of the higher readings is unknown (DOW Measurements of Extreme Winds…, 2003). The Mulhall tornado’s extreme winds formed a giant circle one mile across with a large, calm eye at center. The tornado had hurricane force winds extending over an area four miles across, making it the largest tornado ever analyzed by the DOW. The tornado only caused two fatalities as it swept through largely rural areas north of Oklahoma City, but the storm had the potential to produce a huge swath of E/F4 to E/F5 damage had it struck a heavily populated area.

Image of the Mulhall tornado taken from the DOW. The tornado was rated F4, but had it passed over more structures it likely would have received an F5 rating.

Equal area comparison between the Mulhall and Bridge Creek tornadoes from cswr.org. The Mulhall tornado had similar but slightly weaker winds at the time of analysis but the size of the tornado was remarkable. The tornado’s core missed the center of Mulhall by nearly a mile but the broad region of winds caused severe damage across the town.

Measurements from mobile doppler radars taken before 2007 were often in agreement with the now unused Fujita Scale. Even when the estimates are reduced by 10 to 15% to account for possible altitude effects, the velocities were in agreement with the Fujita Scale. The DOW often found winds higher than the tornado’s damage indicated. Popular opinion now emphasizes being as conservative as possible when estimating tornado windspeeds. The new “Enhanced Fujita Scale” is more specific in its description of tornado damage indicators, but the reduced windspeed ranges likely underestimate the surface winds in violent tornadoes.