Tornado outbreak of February 21–22, 1971

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 47 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.[nb 1][nb 2][nb 3]

Tornado outbreak of February 21–22, 1971
Tornado tracks on February 21–22, 1971
TypeTornado outbreak
DurationFebruary 21–22, 1971
Highest gust50 kn (58 mph; 93 km/h) in Alabama on February 21
Tornadoes
confirmed		≥ 19
Max. rating1F5 tornado
Duration of
tornado outbreak2		1 day, 9 hours, 15 minutes
Largest hail1+3⁄4 in (4.4 cm) in Alabama and Ohio on February 22
Fatalities123 deaths, 1,592 injuries
Damage$45.901 million (1971 USD)
$332 million (2023 USD)
Areas affectedSouthern United States (primarily the Mississippi Delta), Great Lakes region

1Most severe tornado damage; see Fujita scale
2Time from first tornado to last tornado

Background
Surface weather analysis at 12:00 UTC on February 21

At 12:00 UTC on February 21, 1971, surface weather analysis failed to indicate either a well-developed low-pressure area or a defined frontal boundary over the Gulf Coastal Plain, signs that would normally presage a severe weather outbreak. At the time, a diffuse warm front extended eastward from East Texas to portions of Mississippi, and a cold front extended southward over East Texas. Higher up in the atmosphere, conditions were "close to ideal" for a significant tornado outbreak: a broad trough imparted substantial divergence over the prefrontal warm sector.[10]

Impact

Activity started early on the morning of February 21. The first tornadoes touched down in Texas east of Austin and north of Waco. The main activity intensified during the afternoon over the Mississippi and Tennessee Valleys until the late evening hours. At 15:55 UTC the National Severe Storms Forecast Center (NSSFC) in Kansas City, Missouri, issued a tornado watch for eastern Arkansas, northern Mississippi, and adjourning portions of Tennessee and Alabama. A subsequent watch covered portions of eastern Louisiana and southwestern Mississippi, more than an hour before the first major tornado developed.

Upper-air analysis at 12:00 UTC on February 21

Three violent, long-lived tornadoes—two of which may have been tornado families—in western Mississippi and northeastern Louisiana caused most of the deaths along 330 mi (530 km) of path. The first of the three long-lived violent tornadoes was an F5 that touched down in Louisiana and traveled continuously for 102 mi (164 km), followed by an F4 in Mississippi that produced continuous damage for 159 mi (256 km) and continued into Tennessee. A third, F4 tornado traveled 65 mi (105 km) through Little Yazoo, Mississippi, and near Lexington. The three violent tornadoes moved at up to 55 mph (89 km/h), and eyewitnesses reported more than 50 tornadoes or funnel clouds in the Mississippi Delta region alone, many of which were sightings of the same tornado. At one point, the National Weather Service (NWS) WSR-57, a type of weather radar, in Jackson, Mississippi, reported four hook echoes, often indicative of tornado-producing supercells, simultaneously.

Although authorities issued timely tornado warnings—with an average lead time of about an hour in the worst-hit areas—few homes in the area were well constructed, and many lacked basements or other safe areas, thus contributing to the large number of deaths. Many residents were reportedly aware of the danger but could not find shelter in time. As a result, the violent tornadoes killed entire families and caused as many as 21 deaths in some communities. Many of the dead were blacks who resided in frail structures. The entire outbreak may have killed 113–119 people and injured as many as 2,003 others. In Mississippi alone, tornadoes officially killed 110 people and injured 1,469; of these, 454 persons were hospitalized. Some sources listed 107 deaths and 1,060–1,514 injuries in Mississippi.[11]

Outbreak statistics
Outbreak death toll[12]
State Total County County
total
Louisiana 11 Madison 11
Mississippi 110 Humphreys 32
Leflore 14
Sharkey 23
Sunflower 28
Warren 2
Yazoo 11
North Carolina 2 Cumberland 2
Totals 123
All deaths were tornado-related

Confirmed tornadoes
Confirmed tornadoes by Fujita rating
FU F0 F1 F2 F3 F4 F5 Total
0 2 4 7 3 2 1 ≥ 19*
  • The actual total was likely considerably higher, especially over rural areas.[13] The following events may have occurred but were not officially documented and currently do not appear on any official database:
    • On February 21, between 15:25–15:35 UTC, a funnel cloud and possible tornado may have occurred during a severe thunderstorm at Athens, Henderson County, Texas. One resident reported a "roaring" noise like that of many freight trains, but a tornado was not believed to have developed.[14]
    • On February 21, at 00:30 UTC, a tornado may have hit Toccopola, Pontotoc County, Mississippi, according to a report by the National Oceanic and Atmospheric Administration (NOAA).[15]
    • On the same date a 15-mile-long (24 km), 200-yard-wide (180 m; 600 ft) tornado began at 02:31 UTC, near Statesville, Wilson County, Tennessee, and passed through Prosperity before ending at Liberty, in DeKalb County. In all, the tornado destroyed or severely damaged 10 homes, 15 barns, and 14 other structures, along with a spacious brick church. Half a dozen cars were damaged as well, and at least one home lost its roof. Tornado researcher Thomas P. Grazulis listed the tornado as an F3.[16]

February 21 event
Confirmed tornadoes – Sunday, February 21, 1971[nb 4][nb 5]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F2 Bellmead McLennan TX 31.62°N 97.10°W / 31.62; -97.10 (Bellmead (February 21, F2)) 13:30–? 0.1 mi (160 m) 17 yd (16 m) This brief-but-strong tornado struck downtown Bellmead, severely damaging several businesses, some of which lost roofs and walls. A shopping center, a bank, and a post office were among the establishments affected. Additionally, one home had its roof torn off and a trailer was destroyed. Losses totaled $250,000. The National Centers for Environmental Information (NCEI) Storm Events Database incorrectly lists the touchdown as having occurred in Lacy Lakeview.[16][14][18]
F1 SW of Lincoln Lee TX 30.28°N 96.97°W / 30.28; -96.97 (Lincoln (February 21, F1)) 14:15–? 0.3 mi (480 m) 10 yd (9.1 m) A brief, narrow tornado tore off an awning and part of a steel roof, carrying them about 100 ft (33 yd) and pulling three awning posts out of the ground. 2-by-4-inch (51 by 102 mm) lumber pieces were driven into the ground as well and could not be dislodged. Losses totaled $250.[14][19]
F5 SE of County Landing, LA to Inverness, MS to S of Schlater, MS Madison (LA), East Carroll (LA), Issaquena (MS), Sharkey (MS), Washington (MS), Humphreys (MS), Sunflower (MS), Leflore (MS) LA, MS 32.38°N 91.47°W / 32.38; -91.47 (County Landing (February 21, F5)) 20:50–23:10 109.2 mi (175.7 km) 500 yd (460 m) 47 deaths – See section on this tornado – 510 people were injured. The rating is disputed. Grazulis listed 400 injuries.[20][16][21][22][23]
F2 S of Collins to E of McGehee Drew, Chicot, Desha AR 33.45°N 91.57°W / 33.45; -91.57 (Collins (February 21, F2)) 21:00–? 17.1 mi (27.5 km) 300 yd (270 m) Numerous trees were downed. A pair of homes were severely damaged, while a number of others and a municipal park incurred minor impacts. Damage was not continuous and was of low-end F2 intensity at most. Losses totaled $250,000.[16][24][25]
F4 New Fitler, MS to Pugh City, MS to WSW of Poor, TN Issaquena (MS), Sharkey (MS), Humphreys (MS), Leflore (MS), Grenada (MS), Tallahatchie (MS), Yalobusha (MS), Lafayette (MS), Marshall (MS), Benton (MS), Tippah (MS), Hardeman (TN) MS, TN 32.70°N 91.02°W / 32.70; -91.02 (New Fitler (February 21, 1971)) 22:00–02:30 202.1 mi (325.2 km) 100 yd (91 m) 58 deaths – See section on this tornado – 795 people were injured and losses were unknown. Grazulis listed 700 injuries.[16][21][26][27]
F2 E of Colt to Southeastern Wynne St. Francis, Cross AR 35.15°N 90.78°W / 35.15; -90.78 ((February 21, F2)) 23:00–? 4.6 mi (7.4 km) 100 yd (91 m) This tornado damaged many structures, including a brick home and mobile homes. Two barns were destroyed as well. Losses totaled $25,000. Grazulis did not list the tornado as an F2 or stronger.[16][24][28]
F4 SSE of Bovina to Little Yazoo to ESE of Jones Crossing Warren, Yazoo, Holmes MS 32.33°N 90.73°W / 32.33; -90.73 (Bovina (February 21, F4)) 23:06–00:16 65.2 mi (104.9 km) 33 yd (30 m) 13 deaths – The final long-lived violent tornado of the outbreak destroyed barns and homes, including a guest house, near Bovina, as well as approximately 100 pecan trees. One home was obliterated, with only concrete blocks remaining on its foundation, and two people died of injuries. Next, the tornado passed through and destroyed Little Yazoo, where many homes, businesses, and a church were leveled and swept away, resulting in nine fatalities. Beyond Little Yazoo, near Bentonia, the tornado killed two more people. In all, in the Little Yazoo–Bentonia area the tornado leveled 12 homes. In Holmes County, the tornado struck the community of Brozville, extensively damaging homes, barns, chicken coops, and sheds. It finally dissipated near Lexington. In all, the tornado leveled many homes along the path and injured 182 people. Losses were unknown. Grazulis listed 200 injuries and a 70-mile-long (110 km) path, while a report by NOAA indicated that the path was 69 mi (111 km) long.[29]
F3 WNW of Whitney to Parchman to NE of Rome Sunflower MS 33.85°N 90.52°W / 33.85; -90.52 (Whitney (February 21, F3)) 23:30–? 8.6 mi (13.8 km) 33 yd (30 m) 3 deaths – This tornado damaged a number of homes in Parchman. A cotton gin and several tenant homes were wrecked in and near Rome. Losses were unknown. The tornado may have begun half an hour or more earlier than is listed officially. Grazulis classified the tornado as an F2. Both Grazulis and Storm Data only listed two fatalities, though the NCEI listed three. Grazulis also listed five injuries.[16][30][31][32]
F0 SSE of McRaven Hinds MS 32.28°N 90.32°W / 32.28; -90.32 (McRaven (February 21, F0)) 00:54–00:55 0.1 mi (160 m) 33 yd (30 m) A brief touchdown produced little or no damage. Losses were unknown.[33][34]
F2 SSW of Snow Lake Shores Benton MS 34.77°N 89.27°W / 34.77; -89.27 (Snow Lake Shores (February 21, F2)) 01:00–02:00 0.1 mi (160 m) 33 yd (30 m) This tornado may have been produced by the same storm as the Cary–Pugh City F4, but more probably was related to a separate storm, based on an hour-long lapse between reported tornadoes. It downed trees and power lines between Holly Springs and Ashland. Losses were unknown. The tornado may have occurred near 01:40 UTC. Grazulis did not list the tornado as an F2 or stronger.[16][35][36][37]
F1 ENE of Sinai Rankin MS 32.13°N 90.17°W / 32.13; -90.17 (Sinai (February 21, F1)) 01:10–? 0.1 mi (160 m) 33 yd (30 m) With a "loud roar" a brief tornado uplifted a vehicle, crossing a road between Florence and Plain. Losses were unknown.[38][39][40]
F0 Eastern Pearl Rankin MS 32.28°N 89.98°W / 32.28; -89.98 (Pearl (February 21, F0)) 01:35–? 0.1 mi (160 m) 33 yd (30 m) A brief tornado felled utility wires and trees at the McLaurin Shopping Center. Losses were unknown.[41][39][42]
F2 Hurricane Pontotoc MS 34.27°N 88.98°W / 34.27; -88.98 (Hurricane (February 21, F2)) 02:30–? 0.1 mi (160 m) 33 yd (30 m) This narrow-but-strong tornado flung roofing and assorted debris for several hundred yards. A school was wrecked and nearby structures on site were damaged as well, along with a pair of stores and a church. Losses were unknown.[16][39][43]
F2 Southeastern Selmer McNairy TN 35.15°N 88.58°W / 35.15; -88.58 (Selmer (February 21, F2)) 03:35–? 1.5 mi (2.4 km) 67 yd (61 m) This strong tornado destroyed or damaged about 40 homes and 15 businesses. The tornado injured 36 people, of whom six were hospitalized, and caused $21⁄2 million in damage. Grazulis classified the tornado as an F3 and noted $1 million in losses.[16][44][45]

February 22 event
Confirmed tornadoes – Monday, February 22, 1971[nb 4][nb 5]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F1 WSW of Letts Corner to WNW of Greensburg Decatur IN 39.23°N 85.60°W / 39.23; -85.60 (Letts Corner (February 22, F1)) 18:00–18:10 9.1 mi (14.6 km) 80 yd (73 m) This tornado damaged a garage, the upper part of a house, and a pair of barns. An airplane was overturned as well. Two people were injured and losses totaled $25,000.[46][47]
F1 S of Riley to ENE of Wiles Crossroads Calhoun SC 33.62°N 80.80°W / 33.62; -80.80 (Riley (February 22, F1)) 21:20–21:45 11.9 mi (19.2 km) 80 yd (73 m) This tornado passed near St. Matthews, unroofing a pair of small homes and a factory. A "roaring" din was noted. Losses totaled $25,000. Grazulis classified the tornado as an F2.[16][44][48]
F2 ESE of Pancoastburg Fayette, Pickaway OH 39.62°N 83.25°W / 39.62; -83.25 (Pancoastburg (February 22, F2)) 21:25–? 2 mi (3.2 km) 100 yd (91 m) Agricultural outbuildings were damaged near Deer Creek. Losses totaled $25,000. Grazulis did not list the tornado as an F2 or stronger.[16][49][50]
F3 Northern Bexley to NW of Havens Corner Franklin OH 39.97°N 82.93°W / 39.97; -82.93 (Bexley (February 22, F3)) 21:55–? 6.8 mi (10.9 km) 100 yd (91 m) This intense tornado moved through eastern Columbus, producing near-continuous damage for its duration. Numerous homes and warehouses were wrecked, while other structures were unroofed, with losses reaching $21⁄2 million. Seven people were injured. Grazulis classified the tornado as an F2 and noted $24⁄5 million in losses.[16][49][51]
F3 Northwestern Fayetteville to Wade to Falcon to SSW of Sharp Point Cumberland, Sampson, Johnston, Wayne, Wilson, Greene, Pitt, Edgecombe NC 35.08°N 78.92°W / 35.08; -78.92 (Fayetteville (February 22, F3)) 22:30–02:00 85.7 mi (137.9 km) 500 yd (460 m) 2 deaths – This tornado tracked continuously for its first 20 mi (32 km), destroying 40 homes—some of which incurred borderline-F4 damage, with only innermost walls left intact—and damaging another 325. The rest of the path may have involved several distinct, brief tornadoes of weaker intensity. 60 people were injured and losses totaled $23⁄4 million. Grazulis and Storm Data listed 64 injuries. All casualties occurred in the earliest part of the path.[16][52][53][54]

Waverly–Melbourne, Louisiana/Delta City–Inverness–Moorhead, Mississippi
Waverly–Melbourne, Louisiana/Delta City–Inverness–Moorhead, Mississippi
F5 tornado
Damage in Inverness, Mississippi
Max. rating1F5 tornado
Fatalities47 fatalities, 510 injuries
Damageunknown
1Most severe tornado damage; see Fujita scale

This devastating, long-lived tornado—of F5 intensity in Louisiana, F4 in Mississippi—was likely a family of multiple tornadoes. It first appeared aloft northwest of Crowville, Louisiana, before finally touching down south-southeast of Delhi. Shortly after developing, the tornado moved northeastward at an average speed of 52 mph (84 km/h), bypassing the small community of Waverly. Along and northeast of U.S. Route 80, the tornado completely leveled a number of small homes at F5 intensity, though the homes may not have been well constructed. About 3 mi (4.8 km) east of Delhi, on a farmstead in Joes Bayou, it killed 10 people in a family of 12, five of whose bodies were thrown into nearby swamps and not located for weeks. Three other homes, a rural church, and half a dozen large, overhead power lines were destroyed nearby. In all, the tornado destroyed as many as seven homes in the Delhi–Waverly area. After devastating Joes Bayou, the tornado mostly traversed unpopulated, forested country for the remainder of its path in Louisiana. As it continued northeastward, however, the tornado struck the Melbourne settlement on Pecan Road, a short distance south of Transylvania, near Alsatia. At Melbourne the tornado destroyed a pair of mobile homes and seven homes. 13 other mobile homes, 11 outbuildings, and a mature pecan grove were severely damaged as well. Vehicles and agricultural implements were tossed about, but only minor injuries occurred. In all, the tornado killed 11 people and injured 18 others in Louisiana, though some sources do not list the eleventh fatality. After striking Melbourne, the tornado crossed the Mississippi River and entered Mississippi. In 1984 and 1993 tornado researcher Thomas P. Grazulis assessed the tornado as having caused F4 damage in Louisiana, but in 2001 revised this to accept the official F5 rating.

Once in Mississippi, the tornado passed near Mayersville in Issaquena County. As it did so, it began to slowly weaken in intensity. It either began to restrengthen or dissipated and reformed as a new tornado in Sharkey County. This possible new tornado went on to produce F4 damage and retained intensity until dissipation. The tornado killed two people near Cameta and destroyed a cotton gin near Nitta Yuma. The tornado then devastated Delta City, killing seven people and destroying the entire community. The tornado continued northeastward, claiming two additional lives west of Isola. Afterward, it entered the town of Inverness as a large tornado, destroying an estimated 80–90% of the community, killing 21 people, and injuring 200 more. In town the tornado destroyed 125–153 homes, along with 40 other structures. 52 homes were badly damaged as well, 61 businesses were destroyed or damaged, and 30 outbuildings were destroyed on farms. The tornado destroyed the entire central business district, city hall, the three largest churches in town, and entire blocks of frail homes in the African-American section of town; many of these homes were "obliterated." Hundreds of people were left homeless, and railcars were tipped onto their sides. The tornado then leveled the northwestern side of Moorhead, killing four people there before ending near Schlater. In all, the tornado destroyed hundreds of homes along its path. It is the only official F5/EF5 to have hit the state of Louisiana since official tornado records began in 1950 and the only F5/EF5 tornado ever recorded in the month of February, although the F5 rating is disputed as many of the houses destroyed were small and frail. It was also the deadliest F5 tornado since the Candlestick Park tornado in 1966 killed 58 people across Mississippi and Alabama, but was later eclipsed by an EF5 tornado on April 27, 2011, that killed 72 people.[55]

Cary–Gooden Lake–Pugh City–Morgan City–Money, Mississippi/Middleton, Tennessee
Cary–Gooden Lake–Pugh City–Morgan City–Money, Mississippi/Middleton, Tennessee
F4 tornado
Damage in Pugh City, Mississippi
Max. rating1F4 tornado
Fatalities58 fatalities, 795 injuries
1Most severe tornado damage; see Fujita scale

This, the deadliest and longest-lived of the three violent tornadoes, was likely a tornado family. It first touched down just southeast of Fitler, approximately 6–8 mi (9.7–12.9 km) southwest of Cary, and moved northeastward. Just south of Cary, the tornado destroyed the Evanna Plantation, killing 14 people there. The tornado then struck Cary, destroying the entire community. Continuing to the northeast, the tornado struck Gooden Lake, killing seven people there, and then struck Mound Lake Plantation, causing two additional fatalities. The tornado then passed through and completely destroyed the Joe Regh Plantation at Pugh City, reducing frail, low-income housing to "splinters," rolling farm machinery, and killing at least 21 people. Some sources listed an extra fatality at Pugh City. Extensive wind-rowing occurred as frame homes were completely swept away. The tornado killed two more people in Swiftown; six in Morgan City; two a few miles west of Greenwood, near Fort Loring; and four near Money. The tornado may have weakened and reformed into a separate event that passed through or near Avalon, Oxberry, Cascilla, and Tillatoba, causing scattered damage in those communities. Isolated stands of mature trees and willows were twisted, splintered, or prostrated, and outbuildings on farms were damaged. Bits of roofing, insulation, and wallpaper were torn off in Tillatoba.

This tornado then lifted and reformed into one or more tornadoes west of Oxford, destroying more than 31 mobile homes in trailer parks, passing near the University of Mississippi campus, and producing a path of 10 mi (16 km) or longer through the Holly Springs National Forest. This series of tornadoes apparently dissipated and reformed yet again near Abbeville. Areas in and near Oxford reported $500,000 in damage, the worst natural disaster in local history. Between Avalon and the Holly Springs National Forest the path ranged from 200 to 800 yd (600 to 2,400 ft; 180 to 730 m) in width. Yet another or more tornadoes may have caused damage between Bethlehem and Oakland, Mississippi, before continuing into Tennessee, where F3 damage occurred 5 mi (8.0 km) southwest of Middleton; there three homes were damaged, one of which was destroyed, with $40,000 in losses. A 24-by-60-foot (7.3 by 18.3 m) mobile home lost its roof and most of its walls. Several large trees were downed or splintered as well. The tornado dissipated shortly thereafter. Its path was just a few miles east of the areas affected by the F5 tornado for most of its path, and several counties were affected by both tornadoes. With 58 fatalities, the tornado is the deadliest in Mississippi since 1950; however, the deadliest Mississippi tornado on record in the 20th century killed 216 people in 1936.[56]

Non-tornadic effects

The outbreak generated severe thunderstorm winds, from Texas to Kentucky and North Carolina; winds peaked at 50 kn (58 mph; 93 km/h) in Tuscaloosa County, Alabama, on February 21. These strong winds damaged utility lines, vegetation, agricultural outbuildings, warehouses, porches, mobile homes, and barns. At least one built-up roof was partly torn off, along with tar paper. On February 21 at Athens, Henderson County, Texas, vigorous winds caused minor injuries to seven people, all of which took place in trailers. Roofing, a drive-in theater screen, and up to 500 television antennae were downed or otherwise damaged. Hail of up to 1+3⁄4 in (4.4 cm) in diameter was reported in Alabama and Ohio as well, including golfball-sized stones in Cambridge and Toledo, Ohio. The publication Storm Data noted that the hail in Ohio peaked at 1 in (2.5 cm) diameter.[57]

Aftermath, recovery, and records

An internal assessment by the Mississippi Power and Light Company determined that its infrastructure incurred the greatest wind-related damage in the company's history. Roughly half of its transmission towers were damaged in both Sharkey and Humphreys counties.[58]

One of the tornadoes attained F5 intensity in Louisiana, the only such event on record in the state, although the rating is disputed. The entire outbreak is the second-deadliest ever in February, behind only the Enigma tornado outbreak in 1884 and ahead of the 2008 Super Tuesday tornado outbreak. February 21 was the fourth-deadliest day for tornadoes in Mississippi on record.[59]

See also

Notes
  1. 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]
  2. The 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.[2][3] While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007,[4] Canada used the old scale until April 1, 2013;[5] nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.[6]
  3. Historically, the number of tornadoes globally and in the United States was and is likely underrepresented: research by Grazulis on annual tornado activity suggests that, as of 2001, only 53% of yearly U.S. tornadoes were officially recorded. Documentation of tornadoes outside the United States was historically less exhaustive, owing to the lack of monitors in many nations and, in some cases, to internal political controls on public information.[7] Most countries only recorded tornadoes that produced severe damage or loss of life.[8] Significant low biases in U.S. tornado counts likely occurred through the early 1990s, when advanced NEXRAD was first installed and the National Weather Service began comprehensively verifying tornado occurrences.[9]
  4. All 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.
  5. Prior to 1994, only the average widths of tornado paths were officially listed.[17]

References
  1. Schneider, Russell S.; Brooks, Harold E.; Schaefer, Joseph T. (2004). Tornado Outbreak Day Sequences: Historic Events and Climatology (1875–2003) (PDF). 22nd Conf. Severe Local Storms. Hyannis, Massachusetts: American Meteorological Society. Retrieved September 17, 2019.
  2. Grazulis 1993, p. 141.
  3. Grazulis 2001a, p. 131.
  4. 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.
  5. "Enhanced Fujita Scale (EF-Scale)". Environment and Climate Change Canada. June 6, 2013. Archived from the original on March 3, 2016. Retrieved February 25, 2016.
  6. "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on March 5, 2016. Retrieved February 25, 2016.
  7. Grazulis 2001a, pp. 251–4.
  8. Edwards, Roger (March 5, 2015). "The Online Tornado FAQ (by Roger Edwards, SPC)". Storm Prediction Center: Frequently Asked Questions about Tornadoes. Storm Prediction Center. Retrieved February 25, 2016.
  9. Cook & Schaefer 2008, p. 3135.
  10. Multiple sources:
  11. Multiple sources:
  12. Storm Data Publication 1971, Events Reported
  13. Multiple sources:
  14. Storm Data 1971, p. 25.
  15. NOAA 1971, pp. 29, 56.
  16. Grazulis 1993, p. 1121.
  17. Brooks 2004, p. 310.
  18. Storm Data Publication 1971, #10133902
  19. Storm Data Publication 1971, #10134763
  20. Edwards, Roger, ed. (March 19, 2021). "F5 and EF5 Tornadoes of the United States, 1950-present". The Online Tornado FAQ: Frequently Asked Questions about Tornadoes. Norman, Oklahoma: Storm Prediction Center. Retrieved 3 February 2022.
  21. "NWS Jackson, MS - Mar. 3, 2006 40th Anniversary of the Candlestick Park Tornado". Jackson, Mississippi Weather Forecast Office. Flowood, Mississippi: National Weather Service. Retrieved 25 January 2023.
  22. Storm Data 1971, pp. 16, 18.
  23. Multiple sources:
  24. Storm Data 1971, p. 12.
  25. Storm Data Publication 1971, #9982166
  26. Storm Data 1971, pp. 18, 23.
  27. Multiple sources:
  28. Storm Data Publication 1971, #9982167
  29. Multiple sources:
  30. NOAA 1971, p. 49.
  31. Storm Data 1971, p. 18.
  32. Storm Data Publication 1971, #10048644
  33. Storm Data 1971, p. 10.
  34. Storm Data Publication 1971, #10048649
  35. NOAA 1971, p. 56.
  36. Storm Data 1971, pp. 18–19.
  37. Storm Data Publication 1971, #10048650
  38. NOAA 1971, p. 51.
  39. Storm Data 1971, p. 19.
  40. Storm Data Publication 1971, #10048651
  41. NOAA 1971, p. 52.
  42. Storm Data Publication 1971, #10048652
  43. Storm Data Publication 1971, #10048654
  44. Storm Data 1971, p. 23.
  45. Storm Data Publication 1971, #10124730
  46. Storm Data 1971, p. 14.
  47. Storm Data Publication 1971, #10003138
  48. Storm Data Publication 1971, #10110647
  49. Storm Data 1971, p. 22.
  50. Storm Data Publication 1971, #10086663
  51. Storm Data Publication 1971, #10086664
  52. Storm Data 1971, p. 21.
  53. Storm Data Publication 1971, #10088066
  54. Storm Data Publication 1971, #10088067
  55. Multiple sources:
  56. Multiple sources:
  57. Multiple sources:
  58. NOAA & Saltsman 1971, p. 16.
  59. Multiple sources:

Sources
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