A possible tornado damaged a pair of farmsteads southwest of New York Mills in Becker County, Minnesota, causing $3,000 in losses.[12]
Prior to 1990, there is a likely undercount of tornadoes, particularly E/F0–1, with reports of weaker tornadoes becoming more common as population increased. A sharp increase in the annual average E/F0–1 count by approximately 200 tornadoes was noted upon the implementation of NEXRADDoppler weather radar in 1990–1991.[13][note 5] 1974 marked the first year where significant tornado (E/F2+) counts became homogenous with contemporary values, attributed to the consistent implementation of Fujita scale assessments.[17][note 4] Numerous discrepancies on the details of tornadoes in this outbreak exist between sources. The total count of tornadoes and ratings differs from various agencies accordingly. The list below documents information from the most contemporary official sources alongside assessments from tornado historian Thomas P. Grazulis.
Symbol key
Symbol
Description
†
Data from Grazulis
¶
Data from a local National Weather Service office
※
Data from the 1965 Storm Data publication
‡
Data from the NCEI database
♯
Maximum width of tornado
±
Tornado was rated below F2 intensity by Grazulis but a specific rating is unavailable.
This strong tornado impacted Kamp Kiwanis, a Girl Scouts camp, unroofing four cabins and the main structure. A secondary funnel cloud was observed nearby, but was not believed to have developed into a tornado.[21][24][25]
This brief tornado damaged four to six blocks. An unfinished two-story home was unroofed and shorn of its upper story, several rooms of which were found 200 yd (180 m) distant. A commode from the building was found 100 yd (91 m) away as well. The tornado also hurled a 2-by-4-inch (51 by 102 mm) board into a pickup truck. Building insulation spread over the landscape, lodging in crevices and gaps. A shortwave radio transmission tower was toppled as well. The tornado reportedly produced a "jet engine-like" din.[21][24][27]
This strong, long-lived tornado wrecked various outbuildings, sheds, and barns on seven farmsteads. A two-hour discrepancy between reported touchdowns suggests that two separate storms may have been responsible for multiple tornadoes, instead of a single event. The NCEI database lists the start of the path as north-northwest of Woods and the endpoint as west of Brooktree Park.[21][31][36][37][38]
This tornado first touched down beside Lake Darling, wrecking lakeside cottages. It extensively damaged outbuildings on eight farmsteads as well.[21][12][40]
This and the following event may have been part of a single, long-lived tornado family. A dozen or more farmsteads were badly damaged in Minnesota, primarily near Newburg, Lenora, and Canton. Most of the injuries occurred in this area. The tornado apparently lifted near Yucatan and reformed near Money Creek. Near Dakota the tornado wrecked a brick schoolhouse and a number of barns. A car dealership, a school bus, and various buildings were damaged as well. Witnessed by an observer, the tornado crossed the Mississippi River, entering Wisconsin. In the latter state it destroyed buildings on 12 farms. The tornado tossed a vehicle 75 ft (25 yd), injuring a person. The tornado passed between Stevenstown and Mindoro before finally dissipating. In all, seven people were injured, including six in Minnesota.[33][21][44][45][46][47][48]
This violent tornado passed near Cresco, destroying structures on 28 farmsteads. A pair of spacious farmhouses incurred F4-level damage near the end of the path. All of the 11 injuries took place in Mitchell County. Grazulis indicated that more than one tornado occurred, noting that "[T]he funnel was aloft much of the time".[33][21][22][49][50][51][52][53]
This strong tornado may have first developed in Iowa and crossed into Minnesota around 02:55 UTC. It damaged or destroyed approximately 20 farmsteads, a storage shed, and a barn. Grazulis listed a track from the Ostrander–Le Roy area to near Chatfield.[21][12][60]
This brief-but-strong tornado destroyed a shed, granary, barn, and shop. Trees, a tractor, a pair of combines, and four homes were damaged as well, along with a two-way radio and various other antennae. A porch was wrecked, injuring two people beneath.[21][62][63]
This erratic tornado severely damaged or destroyed structures on 25 farmsteads. A school and a church were wrecked as well. The tornado may have actually formed at 00:55 UTC.[21][64][68][67][3]
1 death – This tornado was first sighted aerially, by a pilot near Green Isle. The tornado headed northeastward, downing trees and "leveling" or badly damaging 26 or more farmsteads. A barn-sized herd of cattle was killed, along with a rural farmer, near Hamburg. The tornado grazed Norwood Young America before dissipating. This tornado may have been the same as the Cologne–Orono event. Grazulis listed a path length of 40 mi (64 km) and a mean width of 800 yd (730 m).[33][21][64][69][70][67][3]
This long-tracked tornado, possibly forming over Childress County in the Texas Panhandle, struck the communities of McKnight (then Metcalf), Ron, and Reed. A church, a school, a store, a cotton gin, 10 barns, and six or more homes were destroyed or damaged. Two people were injured.[21][62][71][72]
A few rural fences were damaged. The parent storm may have produced another tornado 25 minutes later near May, in Harper County. The publication Storm Data lists both events as having occurred on May 25.[91][92]
This intense tornado was the first member of a long-tracked, violent tornado family. It hit the outskirts of Boelus (now Howard City), unroofing some barns and homes. Grazulis ranked it F2.[77][98][99]
Producing sporadic damage, this likely tornado family badly hit the Thedford area, where it wrecked one or more barns, but otherwise impacted very remote, sparsely settled areas.[77][98][101]
This violent tornado family belonged to the same storm as the Boelus F3 and consisted of multiple F4s. Numerous farms were swept away along the entire path, especially near Greeley and Bartlett. A few injuries occurred in a basement near Greeley.[103][77][98][104]
This tornado—the first member of a family—began near Fish Lake, destroying a farmhouse and other buildings on 12 farms. Grazulis listed an injury.[77][98][100]
An hour-long storm attended this tornado. According to Storm Data, a "roaring" sound was heard and swirling debris observed, yet a well-defined funnel was markedly absent. Bits of roofing were torn from buildings.[29][109][86]
In its earliest stage the Wewela F5 may have been the same as this tornado. Seven or more ranches lost buildings, including three farmhouses, some of which incurred borderline-F4 damage. At least one entire ranch was obliterated. A car was thrown and rolled 1⁄2 mi (0.80 km).[77][110][111]
A violent tornado leveled an entire farm, including a pair of barns—one concrete, the other wooden—and a few farmhouses. It also mangled machinery and automobiles on site.[77][29][119]
A strong and destructive tornado moved erratically southwestward and westward through the north side of Corsicana. It first severely damaged several institutions in the city, including the Navarro Junior College, which had its gym partially unroofed, the Baptist Student Union, which was unroofed, and the Memorial Hospital. An unoccupied home was destroyed, and apartment complex was also damaged. The tornado the moved into the rural areas west of the city before striking a farmstead, destroying 10 outbuildings and a grain bin, damaging the farmhouse and several other buildings, and uprooting trees. The tornado dissipated shortly thereafter. Losses totaled $250,000.[140]
This was the first of four violent, destructive tornadoes to impact Minneapolis–St. Paul on May 6. According to Grazulis, it was also the same as the Hamburg–Norwood Young America F2, traveled 40 mi (64 km), and may have begun at 00:50 UTC. It first destroyed three barns near Cologne, causing F2 damage in the area; this segment of the path may have actually been a separate tornado and occurred at 01:15 UTC. The tornado quickly intensified and widened near Waconia, reaching a peak width of 1⁄2 to 3⁄4 mi (0.80 to 1.21 km). Trees were snapped and downed in this area. The tornado then may have lifted and dissipated before reforming west of Lake Minnetonka, along Highway 7. Entering the Mound area, the tornado destroyed three outbuildings and 17 homes at Island Park, causing all known fatalities there. The deaths occurred singly, each in a separate home. The tornado leveled a number of homes in the Mound–Island Park area. Subsequently, the tornado struck Spring Park and largely destroyed the Navarre community. In the Spring Park–Navarre area a resort, a number of boats, and about 30 homes were destroyed, 16 of which were at Navarre alone. West of Wayzata the tornado destroyed a barn shortly before dissipating. According to the publication Storm Data the path may have extended as far as Hamel.[141]
The second of the four violent tornadoes to impact the Twin Cities on May 6 may have actually begun 23 minutes earlier than its predecessor. It produced its first damage near Chanhassen, impacting a farmstead. Near Chanhassen the tornado destroyed or damaged 30 homes. A pair of clocks near Chanhassen recorded the time of touchdown as 00:27 UTC. Heading northward, the tornado damaged a shopping center and a lumberyard. Nearing Lotus Lake, the tornado destroyed or damaged 35 homes. 50 additional homes were destroyed or damaged near Christmas Lake. The tornado subsequently attained its maximum intensity in Deephaven. There it destroyed or damaged 100 homes, a number of which were reportedly leveled; of these, some were described as having been "large and expensive", according to a report quoted by Grazulis. After passing through Deephaven, the tornado apparently dissipated. However, sporadic reports of damage suggested that the parent storm continued to generate possible tornadoes. One of these tornadoes reportedly damaged six homes along Highway 100 in Golden Valley, becoming the first of two tornadoes to impact this area on the same day. Another of these tornadoes became known as the third Fridley tornado, causing minor damage at 01:10 UTC. However, neither of these two tornadoes is officially listed, though they were mentioned in the publication Storm Data. Until 1973 U.S. Weather Bureau/National Weather Service (NWS) records listed these tornadoes as well.[142]
This was the first—possibly the second—of three major tornadoes to impact Fridley on May 6. One industrial plant in Fridley, known as Northern Ordinance, may have been hit by all three tornadoes, the third of which is not officially listed; as a result, the factory incurred more than $2 million in losses and was incapacitated for more than a month. The first Fridley tornado began at Northern Ordinance and was widely visible. It soon impacted the primary school-and-park complex in Fridley, along with the Fridley Trailer Court and several hundred homes. Both this and the second Fridley tornado impacted the trailer court, destroying a total of 200 trailers. A female infant was killed at the trailer court while being bathed. At Fridley Junior High School, an evening program was in progress with more than 300 people in attendance when the tornado struck, but only a single injury occurred there. After striking the school and the trailer court, the tornado intensified significantly and attained its peak intensity, striking Spring Lake Park. There the tornado destroyed 150 homes, some of which sustained F4-level damage. Additionally, three-fourths of the businesses in Spring Lake Park were destroyed, and 900 people lost their homes. Contemporaneous reports suggested that the tornado apparently weakened rapidly and dissipated before exiting the town limits, though official records indicate that the tornado ended in southwestern Blaine. Farther on, scattered wind-related damage was reported in connection with the parent storm, at Braham.[143]
Golden Valley–Fridley–Mounds View–Centerville, Minnesota
The last of the four violent tornadoes to hit the Twin Cities on May 6 touched down in Golden Valley, damaging eight businesses and 25 homes in town. The time of its formation is somewhat uncertain and may have been 02:40 UTC. Leaving Golden Valley, the tornado apparently lifted. Damage resumed in Fridley, including the Fridley Trailer Court. In Fridley this, the preceding, and the unofficial third Fridley tornado hit several of the same properties. The second of the two confirmed tornadoes to hit Fridley passed between the paths of the first and unofficial third tornadoes in town. Exiting Fridley, the tornado rapidly intensified. It then struck Mounds View, where damages reached $1 million. All known fatalities and all but eight injuries in association with the tornado occurred there. In all, the tornado destroyed 46 homes in Mounds View, many of which it leveled, causing a loss of $1 million. Six apartments in town were destroyed as well. Once past Mounds View, the tornado produced discontinuous damage. It crossed a number of lakes, including Centerville Lake, and damaged four farmsteads before dissipating. The parent storm continued on and may have produced a separate tornado near Almelund. This possible tornado damaged outbuildings on three farmsteads and splintered trees. However, it was never officially documented and listed as a tornado.[144]
This very large, long-tracked, exceptionally violent tornado—the only official E/F5 on record in South Dakota—formed along or just north of the Nebraska–South Dakota border, very close to Wewela. It then moved north-northeastward through farmland, bypassing the towns of Colome, Gregory, and Winner. It damaged 25 farmsteads, seven of which it destroyed; of these, it caused F5-level damage to two or three. Farm equipment, fencing, a corncrib, feed bunks, a granary, and various outbuildings were also affected, along with 23 homes. One person was critically injured, and losses totaled $21⁄2 million. The tornado was up to 1 mi (1.6 km) wide for much of its path. Both Grazulis and newspapers suggested that the tornado may have begun in Nebraska, with the latter assessing a path length of 15 mi (24 km). The tornado was also accompanied by hail of up to 2 in (5.1 cm) in diameter that covered the ground to a depth of 3 in (7.6 cm), which damaged additional crops and buildings.[145]
This extremely violent tornado family leveled numerous rural farmsteads throughout its course, particularly near Wolbach. Near Petersburg damage temporarily ceased, suggesting two or more tornadoes. At Primrose the tornado rendered all buildings uninhabitable, except for the schoolhouse, "all but erasing" approximately 90% of the town, according to an account excerpted by Grazulis. According to media, homes in Primrose were reduced to bare slabs, businesses were "leveled", and just five structures in downtown remained intact; mature trees were turned into pulpy "matchsticks" and swept away as well. Cars were moved 400–440 yd (1,200–1,320 ft; 0.23–0.25 mi; 0.37–0.40 km), and the body of a truck was tossed and rolled 2 mi (3.2 km). All four fatalities occurred in three homes at Primrose. Papers were found 55 mi (89 km) away. 53 people were injured along the path and losses reached $75 million. The tornado may have occurred a few hours earlier than officially documented. Publications by Grazulis in 1984 and 2001, along with a technical memorandum published by the National Climatic Data Center (NCDC) in 1999, classified the tornado as an F5.[146]
^An outbreak is generally defined as a group of at least six tornadoes (the number sometimes varies slightly according to local climatology) with no more than a six-hour gap between individual tornadoes. An outbreak sequence, prior to (after) the start of modern records in 1950, is defined as a period of no more than two (one) consecutive days without at least one significant (F2 or stronger) tornado.[1]
^ abcdefAll dates are based on the local time zone where the tornado touched down; however, all times are in Coordinated Universal Time and dates are split at midnight CST/CDT for consistency.
^ abThe Fujita scale was devised under the aegis of scientist T. Theodore Fujita in the early 1970s. Prior to the advent of the scale in 1971, tornadoes in the United States were officially unrated.[6][7] Tornado ratings were retroactively applied to events prior to the formal adoption of the F-scale by the National Weather Service.[8] While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007,[9] Canada used the old scale until April 1, 2013;[10] nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.[11]
^ abThe National Oceanic and Atmospheric Administration's Storm Data publication does not list exact damage totals for every event, instead giving damage categories. As such, damage for individual tornadoes is not comprehensive. Cite error: The named reference "NCEI" was defined multiple times with different content (see the help page).
^ abcdeAll starting coordinates are based on the NCEI database and may not reflect contemporary analyses
^ abcdeThe listed width values are primarily the average/mean width of the tornadoes, with those having known maximum widths denoted by ♯. From 1952 to 1994, reports largely list mean width whereas contemporary years list maximum width.[18] Values provided by Grazulis are the average width, with estimates being rounded down (i.e. 0.5 mi (0.80 km) is rounded down from 880 yards to 800 yards.[19][20]
^Edwards, Roger (March 5, 2015). "Enhanced F Scale for Tornado Damage". The Online Tornado FAQ (by Roger Edwards, SPC). Storm Prediction Center. Retrieved February 25, 2016.
^National Weather Service (September 2020). South Dakota Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F1 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Nebraska Event Report: F1 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Arkansas Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Oklahoma Event Report: F1 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Oklahoma Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). South Dakota Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Oklahoma Event Report: F0 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Texas Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Oklahoma Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Texas Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Texas Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
^National Weather Service (September 2020). Texas Event Report: F2 Tornado. Storm Events Database (Report). National Centers for Environmental Information. Retrieved 6 January 2021.
— (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. ISBN1-879362-03-1.
