Tornado outbreak of April 21–24, 1968

On April 21–24, 1968, a deadly tornado outbreak struck portions of the Midwestern United States, primarily along the Ohio River Valley. The worst tornado was an F5 that struck portions of Southeastern Ohio from Wheelersburg to Gallipolis, just north of the Ohio–Kentucky state line, killing seven people and injuring at least 93. Another long-tracked violent tornado killed six people, injured 364 others, and produced possible F5 damage as it tracked along the Ohio River. At least one other violent tornado caused an additional fatality and 33 injuries in Ohio. In the end, at least 26 tornadoes touched down, leaving 14 dead, including five in Kentucky and nine in Ohio.[nb 2][nb 3][nb 4]

Tornado outbreak of April 21–24, 1968
TypeTornado outbreak
DurationApril 21–24, 1968
Highest gust59 kn (68 mph; 109 km/h) on April 23
Tornadoes
confirmed
26 confirmed
Max. rating1F5 tornado
Duration of
tornado outbreak2
3 days and 12 hours
Largest hail5 in (13 cm) on April 23
Fatalities14 fatalities, 525 injuries
Damage$47.433 million (1968 USD)[nb 1]
$399 million (2023 USD)
Areas affectedMidwestern and Southern United States

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

Background

Impact

Outbreak statistics

Impacts by region
Region Locale Deaths Injuries Damages Source
United States Kansas 00$250,000[10]
Kentucky 5378$28,025,000[11]
Louisiana 00$2,500[12]
Michigan 013$5,275,000[13]
North Carolina 00$25,000[14]
Ohio 9131$13,275,000[15]
Oklahoma 02$300,250[16]
Tennessee 01$250,000[17]
Texas 00$30,000[18]
Total 14 525 $47,433,000 [19]

Confirmed tornadoes

Confirmed tornadoes by Fujita rating
FU F0 F1 F2 F3 F4 F5 Total
0 3 10 8 2 2 1 26

April 21 event

Confirmed tornadoes – Sunday, April 21, 1968[nb 5][nb 6]
F# Location County / Parish State Start
coord.
Time (UTC) Path length Max. width Summary
F1 NE of Cedar Valley Logan OK 35.88°N 97.53°W / 35.88; -97.53 (Cedar Valley (April 21, F1)) 10:00–? 0.2 miles (0.32 km) 100 yards (91 m) Tornado partially unroofed a home and tore its porch loose. Walls were damaged as well. The home itself shifted somewhat on its foundation. Tornado also wrenched a tree from the soil and felled it. Fencing and barbed wire were torn apart as well. A 2-by-4-inch (51 by 102 mm) board lodged itself into the ground and could not be removed. Losses totaled $25,000.[21][22]
F2 SW of Medicine Lodge to E of Nashville Barber, Kingman KS 37.40°N 98.40°W / 37.40; -98.40 (Medicine Lodge (April 20, F2)) 21:00–22:10 30.1 miles (48.4 km) 33 yards (30 m) Damage was intermittent along the path. A trailer, post office, farmhouse, and barns were destroyed or damaged. Losses totaled $250,000. NCEI lists the path as starting south-southeast of Nashville and ending east-southeast of Varner, or west-northwest of Waterloo.[23][24][25]
F1 NW of Roxana Kingfisher OK 36.15°N 97.72°W / 36.15; -97.72 (Roxana (April 20, F1)) 23:20–23:45 0.1 miles (0.16 km) 33 yards (30 m) Tornado west of Marshall tore a tin roof off a barn and damaged trees. Losses totaled $250.[26][22]
F2 SW of Shawnee Angelina TX 31.20°N 94.52°W / 31.20; -94.52 (Shawnee (April 20, F2)) 02:00–? 1 mile (1.6 km) 17 yards (16 m) Tornado blew a CBS-type home off its foundation, damaged a barn, and tore roofing shingles off several houses. Tornado also smashed windows and tore screens loose. 34-inch-diameter (1.9 cm) hail attended the parent storm. Losses totaled $2,500. Grazulis did not list the tornado as an F2 or stronger.[27][28][25]

April 22 event

Confirmed tornadoes – Monday, April 22, 1968[nb 5][nb 6]
F# Location County / Parish State Start
coord.
Time (UTC) Path length Max. width Summary
F0 SW of Aspermont Stonewall TX 33.08°N 100.28°W / 33.08; -100.28 (Aspermont (April 22, F0)) 07:00–07:30 0.1 miles (0.16 km) 33 yards (30 m) Tornado touched down over open farmland. Losses were unknown.[29][28]
F1 SW of Ponder Denton TX 33.17°N 97.30°W / 33.17; -97.30 (Ponder (April 22, F1)) 12:40–? 1.5 miles (2.4 km) 20 yards (18 m) Tornado damaged three barns, sheared off a large pecan tree, and downed utility poles and fences. A house shifted on its foundation and sustained broken windows as well. Losses totaled $2,500.[30][28]
F1 NNW of Rhea Mills Collin TX 33.28°N 96.73°W / 33.28; -96.73 (Rhea Mills (April 22, F1)) 13:50–? 0.5 miles (0.80 km) 17 yards (16 m) Tornado southeast of Celina struck at a point 9 mi (14 km) northwest of McKinney and reportedly affected two communities, Chambersville and "Rollins". Tornado ripped off a porch and part of a roof from a farmhouse. A few nearby barns were also unroofed. High tension power lines were downed as well. Losses totaled $25,000.[31][28]
F1 Southwestern Fort Worth Tarrant TX 32.67°N 97.42°W / 32.67; -97.42 (Fort Worth (April 22, F1)) 17:08–17:15 0.3 miles (0.48 km) 20 yards (18 m) Tornado reported east of Benbrook. Losses were unknown.[32][28]
F0 SE of Hobart Kiowa OK 35.02°N 99.08°W / 35.02; -99.08 (Hobart (April 22, F0)) 20:00–20:27 0.1 miles (0.16 km) 33 yards (30 m) Tornado reported. Losses were unknown.[33][22]
F2 Southern Midwest City Oklahoma OK 35.43°N 97.40°W / 35.43; -97.40 (Midwest City (April 22, F2)) 21:50–? 0.1 miles (0.16 km) 17 yards (16 m) Tornado destroyed two hangars at Tinker Air Force Base. Tornado then struck a nearby automobile dealership, unroofing the showroom and showering parked cars with debris. Windows, signage, a car wash, and a used-car lot also incurred damage. A 2-by-12-inch (5.1 by 30.5 cm) rafter traveled 800 ft (270 yd) and pierced a windshield. One person was injured and losses totaled $250,000.[34][35][25]
F1 Northwestern Wilburton Latimer OK 34.92°N 95.35°W / 34.92; -95.35 (Wilburton (April 22, F1)) 23:40–? 3.3 miles (5.3 km) 67 yards (61 m) Tornado damaged or destroyed 11 homes, a barn, and three mobile homes. Power lines and trees were downed as well. One person was injured and losses totaled $25,000. Grazulis classified the tornado as an F2.[36][37][25]

April 23 event

Confirmed tornadoes – Tuesday, April 23, 1968[nb 5][nb 6]
F# Location County / Parish State Start
coord.
Time (UTC) Path length Max. width Summary
F1 Frontier to NNE of Pittsford Hillsdale MI 41.78°N 84.60°W / 41.78; -84.60 (Frontier (April 23, F1)) 17:50–? 9.3 miles (15.0 km) 200 yards (180 m) Tornado damaged 54 cottages and homes. One person was injured and losses totaled $250,000.[38][39]
F4 SW of Falmouth, KY to WNW of Mule Town, OH Pendleton (KY), Bracken (KY), Mason (KY), Brown (OH), Adams (OH), Scioto (OH) KY, OH 38.67°N 84.37°W / 38.67; -84.37 (Falmouth (April 23, F4)) 18:41–? 78.7 miles (126.7 km) 550 yards (500 m) 6 deaths – See section on this tornado – May have been a family of two or three tornadoes and reached F5 intensity at one or more locations. 364 people were injured.[40][41][42][43][44][45][46][25][47]
F3 Big Rapids to E of Marion Mecosta, Osceola MI 43.70°N 85.48°W / 43.70; -85.48 (Big Rapids (April 23, F3)) 18:53–? 60.9 miles (98.0 km) 100 yards (91 m) Tornado family struck the town of Big Rapids. A total of 25 homes and businesses were damaged, causing $500,000 in damage. One home lost its roof and two walls, and several cottages were leveled. Four homes were torn apart east of Paris as well, and extensive damage occurred just east of Marion. 11 people were injured and losses totaled $5 million. Grazulis classified the tornado as an F2.[48][49][39][25]
F4 W of Glen Este to E of Westboro Clermont, Brown, Clinton OH 39.10°N 84.27°W / 39.10; -84.27 (Glen Este (April 23, F4)) 18:56–? 24.1 miles (38.8 km) 300 yards (270 m) 1 death – Large tornado, proceeding at 45 to 50 mph (72 to 80 km/h), passed through or near Glen Este, Willowville, Perintown, and Newtonsville. It destroyed 35 homes, 50 barns, and one house trailer. The tornado attained a peak width of 1,000 yd (0.57 mi; 0.91 km) near Newtonsville. 33 people were injured and losses totaled $7.5 million.[50][51][52][53][25]
F1 SE of Fayette Fulton OH 41.70°N 84.30°W / 41.70; -84.30 (Fayette (April 23, F1)) 19:15–? 0.1 miles (0.16 km) 100 yards (91 m) Trees, power lines, and roofing were damaged. Losses totaled $25,000.[54][53]
F0 Western Livonia Wayne MI 42.37°N 83.42°W / 42.37; -83.42 (Livonia (April 23, F0)) 19:30–? 0.1 miles (0.16 km) 20 yards (18 m) One person was injured and losses totaled $25,000.[55]
F2 ENE of Chatham to Dover Bracken, Mason KY 38.72°N 84.00°W / 38.72; -84.00 (Chatham (April 23, F2)) 19:30–? 0.1 miles (0.16 km) 33 yards (30 m) Secondary tornado struck the same counties already hit by the previous F4. Barns were destroyed in Bracken County. Losses totaled $30. Grazulis did not list the tornado as an F2 or stronger.[56][25]
F1 N of Fursville to NE of Alexandria Licking OH 40.02°N 82.72°W / 40.02; -82.72 (Fursville (April 23, F1)) 20:30–? 8.2 miles (13.2 km) 200 yards (180 m) Tornado formed northwest of Columbia Center, south of Jersey, and bypassed Pataskala. Barns and other outbuildings were extensively damaged or destroyed. A school was partly unroofed and other structures incurred damage to their roofs as well. Losses totaled $250,000.[57][46]
F2 SE of Harrison Furnace to NNW of Pinkerman Scioto OH 38.82°N 82.87°W / 38.82; -82.87 (Harrison Furnace (April 23, F2)) 20:30–? 4.9 miles (7.9 km) 100 yards (91 m) Tornado passed south of Minford and struck the Greater Portsmouth Regional Airport, which was known as Scioto County Airport at the time. 12 aircraft were destroyed or damaged at the airport. One man was severely injured when a CBS-type barn collapsed. Several outbuildings and homes were damaged or destroyed as well. Losses totaled $250,000.[58][46][25]
F1 Southern Smithville DeKalb TN 35.95°N 85.82°W / 35.95; -85.82 (Smithville (April 23, F1)) 20:58–? 0.1 miles (0.16 km) 3 yards (2.7 m) Tornado struck the Miller Heights subdivision in Smithville, unroofing and tearing apart a home. Numerous other structures and three trailers were destroyed or damaged as well. One person was injured and losses totaled $250,000. Grazulis classified the tornado as an F2.[59][60][25]
F5 Wheelersburg to Gallipolis Scioto, Lawrence, Gallia OH 38.70°N 82.80°W / 38.70; -82.80 (Wheelersburg (April 23, F5)) 21:05–? 43 miles (69 km) 400 yards (370 m) 7 deaths – See section on this tornado – Rating disputed. Tornado may have been the same as the South Shore F3. 93 people were injured.[61][62][63]
F2 NNE of Lyons Point Acadia LA 30.13°N 92.35°W / 30.13; -92.35 (Lyons Point (April 23, F2)) 22:00–? 1 mile (1.6 km) 67 yards (61 m) Tornado occurred south of Crowley. One barn was destroyed, a second barn was damaged, and a house trailer was overturned. Losses totaled $2,500. Grazulis did not list the tornado as an F2 or stronger. NCEI lists the touchdown as southwest of Ebenezer.[64][65]
F2 Southern Nicholasville to WNW of Union Mills Jessamine KY 37.87°N 84.58°W / 37.87; -84.58 (Nicholasville (April 23, F2)) 22:34–? 3.3 miles (5.3 km) 60 yards (55 m) Several homes sustained roof damage and one lost its roof entirely. Another home shifted off its foundation. A barn was obliterated and scattered over 60 to 70 acres (24 to 28 ha). Three people were injured and losses totaled $250,000. Grazulis listed six injuries.[66][47][67]

April 24 event

Confirmed tornadoes – Wednesday, April 24, 1968[nb 5][nb 6]
F# Location County / Parish State Start
coord.
Time (UTC) Path length Max. width Summary
F2 SSW of Bayview Beaufort NC 35.42°N 76.8°W / 35.42; -76.8 (Bayview (April 24, F2)) 22:00–? 2 miles (3.2 km) 200 yards (180 m) Intermittent, localized damage affected three separate points. Various outbuildings, barns, and a dwelling were destroyed or damaged. Tornado also twisted apart 2-foot-diameter (61 cm; 0.61 m) trees. Losses totaled $25,000. Grazulis did not list the tornado as an F2 or stronger.[68][67]

Falmouth–Berlin–Bladeston–Chatham–Dover, Kentucky/Ripley–Decatur–Otway, Ohio

Falmouth–Berlin–Bladeston–Chatham–Dover, Kentucky/Ripley–Decatur–Otway, Ohio
F4 tornado
on the Fujita scale
Overall effects
Fatalities6
Injuries364
Damage$27,775,250

This destructive, long-tracked, intense tornado began 1+12 to 2 mi (2.4 to 3.2 km) southwest of Falmouth, Kentucky, and tracked generally eastward or east-northeastward into town at approximately 3:45 p.m. EDT (19:45 UTC). The tornado passed just southeast of the business district, its parent supercell attended by grapefruit-sized hailstones. The tornado damaged 380 homes in Falmouth and 40% of the town itself. 280 homes in Falmouth were described as having been either destroyed or sustained major damage. Four fatalities and 350 injuries occurred in Pendleton County, Kentucky, primarily in and near Falmouth. Crossing into Bracken County, the tornado caused additional damage in or near the communities of Berlin, Bladeston, and Chatham. Across Bracken County about 70 homes were destroyed or damaged and 175 barns were destroyed. One fatality was reported outside Augusta, and eight other people were injured in Bracken County. Entering Mason County, the tornado devastated Dover at 4:15 p.m. EDT (20:15 UTC), severely damaging 115 of 127 houses there. Six trailers and churches were destroyed and three businesses were damaged as well. Eyewitnesses in Dover reported two or three funnel clouds during the passage of the primary tornado. Two injuries occurred in Mason County. In Kentucky the tornado left 500 to 700 people homeless.

The tornado then crossed into Brown County, Ohio, south of Levanna and struck Ripley, where 30 homes were damaged, 40 barns were destroyed, and a tobacco warehouse and a shoe plant were badly damaged. Local reports suggested two separate tornado tracks in the area, one north of Ripley and another through town. One fatality occurred about 3 mi (4.8 km) north of Ripley. The main tornado, moving east-northeastward at about 50 mph (80 km/h), then continued through Brown County, destroying 17 barns near Decatur, before moving through Adams County, where 25 homes and barns were damaged or destroyed and four trailer homes were destroyed. Final reports of damage occurred near Otway and Lucasville in Scioto County. Four people were injured in Brown County. The tornado occasionally lifted as it dipped into valleys but mostly remained on the ground, though it may have been a tornado family. It produced high-end F4 damage and may have been an F5 like the Wheelersburg–Gallipolis event, but is officially rated F4. In all, the tornado injured 364 people and caused $27,775,250 in losses.[69][45][46][25]

South Shore, Kentucky/Wheelersburg–Lyra–Buckhorn–Cadmus–Centenary–Gallipolis, Ohio

South Shore, Kentucky/Wheelersburg–Lyra–Buckhorn–Cadmus–Centenary–Gallipolis, Ohio
Meteorological history
Formedc.5:00 p.m.
April 23, 1968
F5 tornado
on the Fujita scale
Highest winds>316 mph (509 km/h)
Overall effects
Fatalities7
Injuries93
Damage$2,750,030
Areas affectedSouth Shore, KY to Wheelersburg and Gallipolis, Ohio

At around 5:00 p.m. EDT (21:00 UTC), the deadliest tornado of the outbreak touched down in the South Shore, Kentucky area where it caused F3 level damage to multiple homes and trees. The tornado crossed the Ohio River into Ohio, the tornado struck a freight train stationed beside the river, toppling 10 empty coal-hoppers, one of which it lifted 100 ft (30 m; 33 yd). The tornado then affected a combined trucking terminal and garage, a transfer company, a farm supplier, and seven homes at the foot of a hillside. One of the homes was swept from its foundation. Cars were tossed from US 52 as well. The tornado missed downtown Wheelersburg, but peripheral winds downed tree limbs in town, and a number of homes incurred damage as well. Outside Wheelersburg proper, the tornado intensified as it struck the Dogwood Ridge subdivision, causing F5 damage there. Of the 550 homes reportedly destroyed or damaged around Wheelersburg, most were located in the Dogwood Ridge area, approximately 4 mi (6.4 km) east-northeast of town. All known fatalities and 75 injuries occurred in this area. A greenhouse was destroyed and a furniture company had its roof torn off. A large metal power line truss tower was ripped off at the base and thrown by the tornado. Wheelersburg Cemetery was damaged as well.

Meteorological reports suggested that the tornado weakened after passing Dogwood Ridge and only traveled 4 to 5 mi (6.4 to 8.0 km) in Ohio before dissipating. However, official records indicate that the storm moved east into Lawrence and Gallia counties and affected areas near and around the communities of Lyra, Buckhorn, Cadmus, Centenary, and Gallipolis, where the tornado dissipated 34 mi (55 km) after its initial touchdown. One injury occurred in Lawrence County and 17 more in Gallia County. The tornado caused damage in the Gallipolis area before dissipating, where six house trailers, eight homes, and four farm buildings were destroyed. 15 buildings were damaged at the Gallipolis State Institute. In all, the tornado killed seven people, injured 93 others, and caused at least $2,750,030 in damage (1968 USD), approximately $2 million of which occurred in Scioto County alone. Approximately 69 homes and 28 other buildings were destroyed and another 476 structures were damaged. Then-Governor of Ohio Jim Rhodes called in the National Guard to assist the rescue and cleanup efforts. The F5 rating is disputed due to the fact that the homes that were swept away were not properly anchored to their foundations. Some National Weather Service records show that the tornado began with F3-level damage in Greenup County, Kentucky, making its track 43 mi (69 km) in length. This was the first official F5 tornado in Ohio since tornado records began in 1950. Other F5 tornadoes in Ohio took place in Cincinnati and Xenia (near Dayton) on April 3, 1974, and in Niles near Youngstown and Warren on May 31, 1985.[70][71][65][72]

Non-tornadic effects

Hail of up to 5 in (13 cm) in diameter piled 1 ft (0.30 m) high near Baxter, Harlan County, Kentucky, on April 23.[73] Severe thunderstorm winds gusted to 59 kn (68 mph; 109 km/h) in Wayne County, Michigan, on April 23.[74]

Aftermath and recovery

See also

Notes

  1. All losses are in 1968 USD unless otherwise noted.
  2. 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]
  3. 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 utilized the old scale until April 1, 2013;[5] nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.[6]
  4. 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]
  5. 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.
  6. Prior to 1994, only the average widths of tornado paths were officially listed.[20]

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 17 September 2019.
  2. Grazulis 1993, p. 141.
  3. Grazulis 2001a, p. 131.
  4. Edwards, Roger (5 March 2015). "Enhanced F Scale for Tornado Damage". The Online Tornado FAQ (by Roger Edwards, SPC). Storm Prediction Center. Retrieved 25 February 2016.
  5. "Enhanced Fujita Scale (EF-Scale)". Environment and Climate Change Canada. 6 June 2013. Archived from the original on 3 March 2016. Retrieved 25 February 2016.
  6. "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on 5 March 2016. Retrieved 25 February 2016.
  7. Grazulis 2001a, pp. 251–4.
  8. Edwards, Roger (5 March 2015). "The Online Tornado FAQ (by Roger Edwards, SPC)". Storm Prediction Center: Frequently Asked Questions about Tornadoes. Storm Prediction Center. Retrieved 25 February 2016.
  9. Cook & Schaefer 2008, p. 3135.
  10. Multiple sources:
  11. Multiple sources:
  12. Multiple sources:
  13. Multiple sources:
  14. Multiple sources:
  15. Multiple sources:
  16. Multiple sources:
  17. Multiple sources:
  18. Multiple sources:
  19. Multiple sources:
  20. Brooks, Harold E. (April 2004). "On the Relationship of Tornado Path Length and Width to Intensity". Weather and Forecasting. Boston: American Meteorological Society. 19 (2): 310. Bibcode:2004WtFor..19..310B. doi:10.1175/1520-0434(2004)019<0310:OTROTP>2.0.CO;2.
  21. Storm Data Publication 1968, #10094693
  22. Storm Data 1968, p. 36.
  23. Storm Data Publication 1968, #10024841
  24. Storm Data 1968, p. 27.
  25. Grazulis 1993, p. 1096.
  26. Storm Data Publication 1968, #10094697
  27. Storm Data Publication 1968, #10133586
  28. Storm Data 1968, p. 39.
  29. Storm Data Publication 1968, #10133588
  30. Storm Data Publication 1968, #10133589
  31. Storm Data Publication 1968, #10133590
  32. Storm Data Publication 1968, #10133594
  33. Storm Data Publication 1968, #10094702
  34. Storm Data Publication 1968, #10094711
  35. Storm Data 1968, pp. 36–7.
  36. Storm Data Publication 1968, #10093564
  37. Storm Data 1968, p. 37.
  38. Storm Data Publication 1968, #10040713
  39. Storm Data 1968, p. 30.
  40. Storm Data Publication 1968, #10038065
  41. Storm Data Publication 1968, #10033531
  42. Storm Data Publication 1968, #10033539
  43. Storm Data Publication 1968, #10083175
  44. Storm Data Publication 1968, #10083176
  45. Storm Data 1968, p. 28.
  46. Storm Data 1968, p. 34.
  47. "Tornadoes of 1968". Louisville, KY Weather Forecast Office. Louisville, Kentucky: National Weather Service. Retrieved 3 May 2021.
  48. Storm Data Publication 1968, #10040714
  49. Storm Data Publication 1968, #10040715
  50. Storm Data Publication 1968, #10083172
  51. Storm Data Publication 1968, #10083174
  52. Storm Data Publication 1968, #10083177
  53. Storm Data 1968, p. 33.
  54. Storm Data Publication 1968, #10083173
  55. Storm Data Publication 1968, #10040716
  56. Storm Data Publication 1968, #10033540
  57. Storm Data Publication 1968, #10083183
  58. Storm Data Publication 1968, #10083184
  59. Storm Data Publication 1968, #10124215
  60. Storm Data 1968, p. 38.
  61. Storm Data Publication 1968, #10083187
  62. Storm Data Publication 1968, #10083189
  63. Storm Data Publication 1968, #10083190
  64. Storm Data Publication 1968, #10033104
  65. Grazulis 1993, pp. 1096–7.
  66. Storm Data Publication 1968, #10033556
  67. Grazulis 1993, p. 1097.
  68. Storm Data Publication 1968, #10087458
  69. Multiple sources:
  70. Multiple sources:
  71. Lott, McCown & Ross 2000, p. 14.
  72. Grazulis 2001b, p. 24.
  73. Multiple sources:
  74. Storm Data Publication 1968, #10040718

Sources

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