Tornado outbreak sequence of December 18–20, 1957

On December 18–20, 1957, a significant tornado outbreak sequence affected the southern Midwest and the South of the contiguous United States. The outbreak sequence began on the afternoon of December 18, when a low-pressure area approached the southern portions of Missouri and Illinois. Supercells developed and proceeded eastward at horizontal speeds of 40 to 45 miles per hour (64 to 72 km/h), yielding what was considered the most severe tornado outbreak in Illinois on record so late in the calendar year. Total losses in the state were estimated to fall within the range of $8–$10 million.[4][5][nb 2][nb 3][nb 4]

Tornado outbreak sequence of December 18–20, 1957
TypeTornado outbreak sequence
DurationDecember 18–20, 1957
Highest gust53 kn (61 mph; 98 km/h) (estimated) in Hannibal, Missouri, on December 18[1]
Tornadoes
confirmed		37 confirmed
Max. rating1F5 tornado
Duration of
tornado outbreak2		1 day and 141⁄2 hours
Largest hail1+1⁄4 in (3.2 cm) in diameter in Missouri on December 18[2]
Fatalities19 fatalities, 291 injuries
Damage$15,855,000 (1957 USD)[nb 1][3]
$165 million (2023 USD)
Areas affectedMidwestern and Southern United States, especially eastern Missouri and Southern Illinois

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

Background

At 6:00 a.m. CST (12:00 UTC) on December 18, 1957, a vigorous shortwave trough entered the Great Plains with a cold front moving east across Oklahoma and Kansas. A dissipating stationary front over Oklahoma underwent frontolysis and later redeveloped as a warm front which extended across central Illinois. By 3:00 pm. CST (21:00 UTC), surface dew points reached the low 60s °F across portions of southeast Missouri and southern Illinois, including the St. Louis area. Although most areas were then recording overcast weather conditions, a strong upper-level jet stream helped impart synoptic-scale lifting, a factor that favors updrafts, and little vertical mixing occurred, so instability remained favorable for thunderstorm development. Additionally, very cold temperatures following a surface cyclone raised the lifted index to −6 due to high adiabatic lapse rates. Wind speeds at the middle level of the atmosphere, just under 6 kilometres (3.7 mi) from the ground, were close to 70 mph (110 km/h) as well. Conditions were therefore very conducive to a large tornado outbreak on the afternoon of December 18.[15][16][17]

Similarly favorable conditions occurred a day later, as a warm and moist air mass spread northward from the Gulf of Mexico. In fact, temperatures in the Mississippi Valley and the upper Midwest approached record highs for December. St. Louis and Detroit, recorded afternoon highs of 57 °F (14 °C), while Chicago measured 56 °F (13 °C), only eight degrees lower than the local record high for December 19. Local residents and meteorologists described temperatures as being "springlike" for the time of year, even though meteorological winter was due to begin on December 23. Farther south, temperatures along the Gulf Coast reached the low 70s °F. Just as on December 18, a second tornado outbreak occurred in a broad warm sector from Arkansas to Illinois and south to Alabama.[18]

Confirmed tornadoes
Impacts by state
State Deaths Injuries Damage Ref
Alabama 07$[19][20][21]
Arkansas 29$[22][20][21]
Illinois 13269$[23][20][21]
Missouri 44$[24][20][21]
Tennessee 02$[25][20][21]
Total 19 291 $15,855,000 [3][20][21]
Confirmed tornadoes by Fujita rating
FU F0 F1 F2 F3 F4 F5 Total
0 0 8 16 9 3 1 37

December 18 event
Confirmed tornadoes – Wednesday, December 18, 1957[nb 5][nb 6][3]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F1 WSW of Truxton Lincoln MO 39.00°N 91.25°W / 39.00; -91.25 (Truxton (December 18, F1)) 18:30–? 0.3 miles (0.48 km) 100 yards (91 m) Brief tornado unroofed three homes, one of which it dislodged, injuring a woman inside. Losses totaled $25,000. Tornado researcher Thomas P. Grazulis classified the tornado as an F2.[27][28][29]
F2 ENE of Knob Lick to WSW of Libertyville St. Francois MO 37.68°N 90.35°W / 37.68; -90.35 (Libertyville (December 18, F2)) 19:50–? 2.7 miles (4.3 km) 33 yards (30 m) 1 death – Tornado leveled barns and silos in its path through three farms north of Fredericktown, destroying a home and killing an infant inside. One person was injured and losses totaled $25,000. Grazulis classified the tornado as an F3.[30][28][29]
F3 SE of Diamond Cross to NE of Conant Randolph, Perry IL 37.97°N 89.82°W / 37.97; -89.82 (Diamond Cross (December 18, F3)) 20:40–? 20.2 miles (32.5 km) 33 yards (30 m) Intense tornado produced intermittent damage near Chester, Steeleville, Cutler, Jamestown, and Conant. Tornado affected 10 farmsteads, destroyed one home, and damaged numerous buildings. Losses totaled $25,000.[31][28][29]
F2 ESE of McBride Perry MO 37.83°N 89.83°W / 37.83; -89.83 (McBride (December 18, F2)) 21:00–? 0.5 miles (0.80 km) 50 yards (46 m) Strong tornado momentarily lifted, set down, and shifted an occupied elementary school, but none of the 32 students in attendance was injured. Tornado also destroyed or damaged 15–20 structures on farms, including a number of barns. Losses totaled $250,000.[32][28][29]
F3 SE of Chester to NW of Denmark Randolph, Perry IL 37.90°N 89.80°W / 37.90; -89.80 (Chester (December 18, F3)) 21:15–? 17.7 miles (28.5 km) 33 yards (30 m) Tornado destroyed or damaged at least 24 homes in Willisville, along with the local brick high school. Losses totaled $250,000.[33][28][29]
F2 Northern Roxana Madison IL 38.85°N 90.08°W / 38.85; -90.08 (Wood River (December 18, F2)) 21:20–? 1 mile (1.6 km) 33 yards (30 m) Intense, brief tornado may have first touched down near Florissant, Missouri, before destroying or damaging nine buildings on the southern outskirts of Wood River. One person was injured and losses totaled $25,000. Grazulis classified the tornado as an F3.[34][28][29]
F1 Mason City Mason IL 40.20°N 89.70°W / 40.20; -89.70 (Mason City (December 18, F1)) 21:35–? 0.1 miles (0.16 km) 33 yards (30 m) Brief tornado caused minimal damage to three or four buildings. One person was injured and losses totaled $25,000.[35][28]
F3 NNE of Cutler Perry IL 38.08°N 89.55°W / 38.08; -89.55 (Cutler (December 18, F3)) 21:35–? 2.5 miles (4.0 km) 33 yards (30 m) Tornado destroyed or damaged six homes near the Illinois Routes 154–150 crossroads. Cars were blown off the highways and destroyed. One person was injured and losses totaled $250,000.[36][28][29]
F2 NW of Boyd to SSE of Dix Jefferson IL 38.42°N 89.02°W / 38.42; -89.02 (Boyd (December 18, F2)) 21:45–? 4.5 miles (7.2 km) 33 yards (30 m) Tornado unroofed or extensively damaged eight structures. Two people were injured and losses totaled $25,000. Tornado may have dissipated near Kell.[37][28][38]
F4 S of Roaches to NNE of Marlow Jefferson IL 38.28°N 89.08°W / 38.28; -89.08 (Roaches (December 18, F4)) 21:55–22:10 16.8 miles (27.0 km) 250 yards (230 m) 1 death – See section on this tornado – 45 people were injured and losses totaled $2.5 million.[39][28][38]
F2 NNW of Ava to ENE of Sato Jackson IL 37.90°N 89.50°W / 37.90; -89.50 (Ava (December 18, F2)) 22:00–? 5.4 miles (8.7 km) 33 yards (30 m) Tornado damaged three or four properties. Losses totaled $25,000. Grazulis did not list the event as an F2 or stronger.[40][28][20]
F3 ESE of Belgique, MO to WNW of Degognia, IL Randolph IL 37.83°N 89.75°W / 37.83; -89.75 (Belgique (December 18, F3)) 22:15–? 5.7 miles (9.2 km) 33 yards (30 m) Tornado passed near Rockwood, Illinois, flipping freight cars and damaging nearby buildings. Losses totaled $25,000. Grazulis did not list the event as an F2 or stronger.[41][42][20]
F2 E of Woodlawn to ENE of Camp Ground Jefferson IL 38.33°N 89.02°W / 38.33; -89.02 (Woodlawn (December 18, F2)) 22:30–? 11.6 miles (18.7 km) 200 yards (180 m) Tornado impacted the northernmost outskirts of Mount Vernon as it damaged 12 structures. Losses totaled $25,000. Grazulis classified the tornado as an F3.[43][42][38]
F5 NNW of Sunfield to ESE of Tamaroa Perry IL 38.08°N 89.25°W / 38.08; -89.25 (Sunfield (December 18, F5)) 22:35–? 5.4 miles (8.7 km) 200 yards (180 m) 1 death – See article on this tornado – Six people were injured.[44][42][38]
F2 E of Scopus to NE of Pocahontas Cape Girardeau MO 37.40°N 89.87°W / 37.40; -89.87 (Scopus (December 18, F2)) 22:45–22:55 15.8 miles (25.4 km) 700 yards (640 m) Intense tornado passed near Millersville, Oak Ridge, and Highway 61, affecting five farmsteads, one of which lost its farmhouse and all barns. One person was injured and losses totaled $250,000. Grazulis classified the tornado as an F3.[45][46][42][38]
F4 Gorham to Plumfield Jackson, Williamson, Franklin IL 37.70°N 89.48°W / 37.70; -89.48 (Happy Hollow (December 18, F4)) 22:45–23:05 28.3 miles (45.5 km) 300 yards (270 m) 11 deaths – See section on this tornado – 200 people were injured and losses totaled $7.5 million.[47][48][49][38]
F2 N of Altenburg Perry MO 37.68°N 89.58°W / 37.68; -89.58 (Altenburg (December 18, F2)) 23:00–? 1 mile (1.6 km) 10 yards (9.1 m) Brief tornado destroyed a home near Altenburg. Losses totaled $25,000. Grazulis classified the tornado as a high-end F3.[50][29]
F3 ESE of Orchardville to Southern Clay City Wayne, Clay IL 38.50°N 88.63°W / 38.50; -88.63 (Orchardville (December 18, F3)) 23:00–? 19.6 miles (31.5 km) 200 yards (180 m) Tornado, its trajectory varying from east-northeast to northeast, destroyed or damaged structures on 20 farmsteads. One person was injured and losses totaled $500,000. Another, unconfirmed tornado may have hit the same area at 22:30 UTC.[51][52][42][38][53]
F2 Chaffee Scott MO 37.18°N 89.67°W / 37.18; -89.67 (Chaffee (December 18, F2)) 23:22–? 0.5 miles (0.80 km) 33 yards (30 m) 3 deaths – One or more tornadoes, possibly paralleling each other, destroyed or unroofed a shoe factory, businesses, and homes. All fatalities occurred in a small home. At least one person—possibly three others—was injured and losses totaled $2.5 million.[54][38]
F2 Carbondale Jackson IL 37.70°N 89.22°W / 37.70; -89.22 (Carbondale (December 18, F2)) 23:25–? 1.5 miles (2.4 km) 33 yards (30 m) Tornado touched down near Southern Illinois University, destroying 15 trailers and damaging three other homes. Five people were injured and losses totaled $2,500. Grazulis did not list the tornado as an F2 or stronger.[55][42][20]
F3 W of Ste. Marie to ESE of Willow Hill Jasper IL 38.93°N 88.05°W / 38.93; -88.05 (Ste. Marie (December 18, F3)) 23:25–? 4.5 miles (7.2 km) 33 yards (30 m) Tornado damaged four farmsteads and destroyed one or more barns in a limited area between Boos and Ste. Marie. Losses totaled $25,000.[56][42][38]
F3 Southeastern Dahlgren Hamilton IL 38.20°N 88.70°W / 38.20; -88.70 (Dahlgren (December 18, F3)) 23:35–? 2.5 miles (4.0 km) 150 yards (140 m) Tornado destroyed or extensively damaged several homes. Tornado may have formed from the same supercell as the Sunfield F5. Three people were injured and losses totaled $250,000.[57][42][38]
F3 SW of Springerton to NW of Grayville Hamilton, White, Edwards IL 38.17°N 88.42°W / 38.17; -88.42 (Springerton (December 18, F3)) 00:00–? 19.8 miles (31.9 km) 33 yards (30 m) Tornado affected 20 farmsteads, destroying four or more barns and a home. Four people were injured and losses totaled $250,000.[58][38]
F2 Forman Johnson IL 37.30°N 88.92°W / 37.30; -88.92 (Karnak (December 18, F2)) 00:00–? 0.1 miles (0.16 km) 33 yards (30 m) Tornado destroyed one church and struck a school and two farms. Two tornadoes were probably involved but the event is not officially listed as such. Losses totaled $25,000.[59][42][38]
F1 SE of Sidell to W of Indianola Vermilion IL 39.90°N 87.80°W / 39.90; -87.80 (Sidell (December 18, F2)) 00:40–? 3 miles (4.8 km) 60 yards (55 m) This tornado was apparently heard to produce a "'roaring'" noise with minimal damage.[60][42]

December 19 event
Confirmed tornadoes – Thursday, December 19, 1957[nb 5][nb 6][3]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F4 E of Waldo to N of Stephens Columbia, Ouachita AR 33.35°N 93.25°W / 33.35; -93.25 (Waldo (December 19, F4)) 18:44–? 17.7 miles (28.5 km) 33 yards (30 m) 2 deaths – This violent tornado produced F4 damage as it touched down at "Cotton Belt", a community between Waldo and McNeil. There, five homes were levelled and a boy killed and thrown 250 yd (750 ft) from his home. Elsewhere, the tornado damaged five other homes. The tornado also threw and rolled a car 600 yd (0.34 mi) just before dissipating, having caused nine injuries and destroyed eight buildings.[61][62][63][38]
F1 S of Milan Gibson TN 35.87°N 88.75°W / 35.87; -88.75 (Sitka (December 19, F1)) 21:00–? 0.1 miles (0.16 km) 7 yards (6.4 m) A brief tornado destroyed four tenant homes on a farm in the Sitka community, south of Milan.[63][64]
F3 Sherrill to SE of Tucker Jefferson AR 34.38°N 91.95°W / 34.38; -91.95 (Sherrill (December 19, F3)) 21:40–? 3.8 miles (6.1 km) 100 yards (91 m) This intense tornado affected two farmsteads and struck the Tucker State Prison Farm.[63][65][38]
F2 SE of Golden City Dade MO 37.37°N 94.07°W / 37.37; -94.07 (Golden City (December 19, F2)) 22:10–22:15 6.6 miles (10.6 km) 100 yards (91 m) This tornado intermittently damaged five farmsteads. The tornado alternately lifted and touched down, and a number of funnel clouds were reported, so more than one tornado may have been involved. Grazulis did not list this tornado as an F2 or stronger.[63][66][20]
F2 Waltonville Jefferson IL 38.20°N 89.05°W / 38.20; -89.05 (Waltonville (December 19, F2)) 23:50–? 1 mile (1.6 km) 67 yards (61 m) This tornado extensively damaged one farm and caused lesser damage to a number of structures. Grazulis did not list this tornado as an F2 or stronger.[63][67][20]
F2 Pankeyville Saline IL 37.70°N 88.53°W / 37.70; -88.53 (Pankeyville (December 19, F2)) 03:00–? 0.5 miles (0.80 km) 100 yards (91 m) A tornado damaged a barn and other buildings south of Harrisburg. Grazulis did not list this tornado as an F2 or stronger.[63][68][20]
F2 Humboldt Gibson TN 35.82°N 88.92°W / 35.82; -88.92 (Humboldt (December 19, F2)) 03:15–? 0.5 miles (0.80 km) 10 yards (9.1 m) A hotel and the local city hall were partially or entirely unroofed. Four tenant homes, a warehouse, and a CBS-built garage were wrecked. A cotton gin and a building sustained damage, the latter of which was also shifted and twisted. Electrical wires and TV antennae were downed as well. Flying debris damaged numerous structures.[63][69]
F1 Milan Gibson TN 35.92°N 88.75°W / 35.92; -88.75 (Milan (December 19, F1)) 03:20–? 0.1 miles (0.16 km) 7 yards (6.4 m) This tornado, the second to hit the Milan area on December 19, damaged roofs, windows, and antennae. Flying debris injured two people. The tornado may have originated from the same storm as the previous event.[63][70]
F1 S of Winfield Fayette AL 33.87°N 87.80°W / 33.87; -87.80 (Winfield (December 19, F1)) 04:30–? 0.1 miles (0.16 km) 33 yards (30 m) This brief tornado destroyed a home and several outbuildings.[71][72]
F2 Littleville Colbert AL 34.60°N 87.67°W / 34.60; -87.67 (Littleville (December 19, F2)) 05:15–? 0.1 miles (0.16 km) 33 yards (30 m) This tornado destroyed or damaged fifteen homes, seven businesses, and the local city hall. Damage neared F3-level intensity. Seven people were injured.[73]

December 20 event
Confirmed tornadoes – Friday, December 20, 1957[nb 5][nb 6][3]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F1 Clanton Chilton AL 32.80°N 86.65°W / 32.80; -86.65 (Clanton (December 20, F1)) 08:53–? 0.1 miles (0.16 km) 33 yards (30 m) This tornado unroofed or extensively damaged twenty to thirty-five homes, three of which were destroyed, and a cotton mill. Grazulis classified the tornado as an F2.[71][74]
F1 E of Castleberry Conecuh AL 31.30°N 86.88°W / 31.30; -86.88 (Castleberry (December 19, F1)) 09:00–? 0.8 miles (1.3 km) 33 yards (30 m) This tornado damaged two areas about 1⁄2 mi (0.80 km) apart. It destroyed two homes and one barn. Grazulis classified the tornado as an F2.[71][75]

Mount Vernon, Illinois
Mount Vernon, Illinois
F4 tornado
Max. rating1F4 tornado
Fatalities1 fatality, 45 injuries
1Most severe tornado damage; see Fujita scale

The second deadly tornado to develop on December 18 became one of two tornadoes to strike Mount Vernon in Jefferson County, Illinois. The first tornado was the strongest and formed at 3:55 pm. CST (21:55 UTC) about 10 mi (16 km) west-southwest of downtown Mount Vernon, whence local police monitored its movement from patrol vehicles and disseminated reports via radio. As the tornado approached downtown Mount Vernon, it completely levelled small, "prefabricated", ranch-style homes in southwest Mount Vernon; damage in this area was later rated F4 by meteorologists, though on the low end of the category. Thereafter, the tornado weakened as it neared downtown Mount Vernon and may have even dissipated before reforming as a separate tornado to the north. It then continued on a skipping path and caused less severe damage to older homesites northeast of Mount Vernon. In Mount Vernon, the tornado damaged or destroyed about fifteen to twenty buildings, including the Block Grade School, where students left only half an hour beforehand. The funnel was described as being "swirling black clouds", filled with debris, that vanished northwest of downtown Mount Vernon. The tornado was up to 250 yd (230 m) wide at times.[28][76]

Gorham–Sand Ridge–Murphysboro–Plumfield, Illinois
Gorham–Sand Ridge–Murphysboro–Plumfield, Illinois
F4 tornado
Max. rating1F4 tornado
Fatalities11 fatalities, 200 injuries
1Most severe tornado damage; see Fujita scale

This tornado, the deadliest of the outbreak sequence, closely resembled the 1925 Tri-State tornado and affected some of the same areas that were hit in 1925, including locations in and near Gorham, Sand Ridge, Murphysboro, and De Soto. It may have touched down in eastern Missouri but was first observed at 4:45 pm. CST (some sources say 4:30 pm. CST) in Gorham, destroying or damaging forty homes there. One fatality occurred in nearby Sand Ridge. As it neared and passed through the southeast side of Murphysboro, the tornado paralleled the Big Muddy River, moving east-northeast. It produced the worst damage, which was rated F4, in this area, destroying old buildings; however, the most intense damage only affected a small section of southeast Murphysboro, where 10 of the 11 deaths occurred. Afterward, the tornado continued on to damage parts of De Soto, Hurst, and Bush. The tornado was last reported near Plumfield at 5:05 pm. CST (23:05 UTC). Murphysboro was powerless for almost three days as most utilities were in the worst-hit area. The tornado injured two hundred people along its path.[3][42][29][76]

Non-tornadic effects

Severe thunderstorms in connection with the outbreak on December 18 produced hail up to 3⁄4 in (1.9 cm) in diameter in St. Francois County, Missouri. Severe winds estimated at up to 60 mph (97 km/h) also affected the Hannibal area in that state, downing power lines and wires. In addition to the six known tornadoes in Missouri, unconfirmed reports of tornadoes occurred in Jefferson County, along with many reports of funnel clouds elsewhere in the state. Other unconfirmed tornadoes were reported in other states, including an alleged tornado that hit Rockville, Indiana. On December 19, a dust storm with 50-mile-per-hour (80 km/h) wind gusts tossed three roofs onto vehicles and reduced visibility to just 1⁄2 mi (0.80 km) in Dallas, Texas. In addition to the three confirmed tornadoes that hit the state that day, severe winds in Tennessee, reportedly unrelated to tornado activity, destroyed farm buildings, tore off roofs, and downed trees and electrical wires; though these may have been due to tornadoes, none was confirmed. In addition to two confirmed tornadoes, unconfirmed reports of tornado damage arrived from Royalton and Elkville, Illinois; though attributed to thunderstorm winds, these damages may have been due to tornadoes. Additionally, severe thunderstorm activity on December 18–19 contributed to severe flood conditions across parts of southern Illinois and in Missouri.[76][18][42][77][63][28]

Aftermath and recovery

After severe weather left the Murphysboro area in Illinois, police officers, firefighters, deputies, and other assistance were called out to the worst-hit subdivisions, Country Heights and Crown View. Then-Illinois Director of Public Health Dr. Roland Cross also sent for the hard-hit Mount Vernon area. Then-Governor of Illinois William G. Stratton directed Illinois state police to the affected areas of southern Illinois and also readied the Illinois National Guard for possible deployment to the region.[76]

See also

Notes
  1. All losses are in 1957 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.[6]
  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.[7][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]
  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.[12] Most countries only recorded tornadoes that produced severe damage or loss of life.[13] 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.[14]
  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.[26]

References
  1. Storm Data Publication 1957, #10062408
  2. Storm Data Publication 1957, #10060860
  3. Storm Data Publication 1957, Events Reported
  4. Joos 1957, p. 160.
  5. Wilson & Changnon 1971, p. 39.
  6. 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.
  7. Grazulis 1993, p. 141.
  8. Grazulis 2001a, p. 131.
  9. 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.
  10. "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.
  11. "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on March 5, 2016. Retrieved February 25, 2016.
  12. Grazulis 2001a, pp. 251–4.
  13. 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.
  14. Cook & Schaefer 2008, p. 3135
  15. Finch, Jonathan D. (November 13, 2005). "Historical Tornado Cases for Saint Louis County Warning Area of Eastern Missouri and SW Illinois". Bangladesh Tornadoes. Archived from the original on May 15, 2006. Retrieved December 27, 2012.
  16. Finch, Jonathan D. "Historical Tornado Cases for North America, 1950–1959". Bangladesh Tornadoes. Archived from the original on July 22, 2011. Retrieved December 27, 2012.
  17. "U.S. Daily Weather Maps". NOAA Central Library. NOAA Central Library Data Imaging Project. National Oceanic and Atmospheric Administration. Retrieved December 11, 2019.
  18. "2 Die in Arkansas in New Tornadoes". The New York Times. Associated Press. December 20, 1957. p. 56.
  19. Storm Data Publication 1957, Events Reported
  20. Grazulis 1993, pp. 1012–3.
  21. USWB 1957, pp. 526–9.
  22. Storm Data Publication 1957, Events Reported
  23. Storm Data Publication 1957, Events Reported
  24. Storm Data Publication 1957, Events Reported
  25. Storm Data Publication 1957, Events Reported
  26. Brooks 2004, p. 310.
  27. Storm Data Publication 1957, #10062409
  28. USWB 1957, p. 526.
  29. Grazulis 1993, p. 1012.
  30. Storm Data Publication 1957, #10060858
  31. Storm Data Publication 1957, #10008653
  32. Storm Data Publication 1957, #10060859
  33. Storm Data Publication 1957, #10008654
  34. Storm Data Publication 1957, #10008655
  35. Storm Data Publication 1957, #10008656
  36. Storm Data Publication 1957, #10008657
  37. Storm Data Publication 1957, #10008658
  38. Grazulis 1993, p. 1013.
  39. Storm Data Publication 1957, #10008659
  40. Storm Data Publication 1957, #10008661
  41. Storm Data Publication 1957, #10008662
  42. USWB 1957, p. 527.
  43. Storm Data Publication 1957, #10008663
  44. Storm Data Publication 1957, #10008664
  45. Storm Data Publication 1957, #10060861
  46. Storm Data Publication 1957, #10060862
  47. Storm Data Publication 1957, #10008665
  48. Storm Data Publication 1957, #10008671
  49. Storm Data Publication 1957, #10008672
  50. Storm Data Publication 1957, #10060863
  51. Storm Data Publication 1957, #10008666
  52. Storm Data Publication 1957, #10008668
  53. Wilson & Changnon 1971, p. 40.
  54. Storm Data Publication 1957, #10060864
  55. Storm Data Publication 1957, #10008667
  56. Storm Data Publication 1957, #10008669
  57. Storm Data Publication 1957, #10008670
  58. Storm Data Publication 1957, #10008674
  59. Storm Data Publication 1957, #10008673
  60. Storm Data Publication 1957, #10009739
  61. Storm Data Publication 1957, #9980864
  62. Storm Data Publication 1957, #9980865
  63. USWB 1957, p. 528
  64. Storm Data Publication 1957, #10124064
  65. Storm Data Publication 1957, #9980866
  66. Storm Data Publication 1957, #10060865
  67. Storm Data Publication 1957, #10009740
  68. Storm Data Publication 1957, #10009741
  69. Storm Data Publication 1957, #10124067
  70. Storm Data Publication 1957, #10124068
  71. USWB 1957, p. 529
  72. Storm Data Publication 1957, #9977951
  73. Storm Data Publication 1957, #9977952
  74. Storm Data Publication 1957, #9977953
  75. Storm Data Publication 1957, #9977954
  76. "Tornadoes Kill 8 in Midwest Area". The New York Times. United Press. December 19, 1957. p. 63.
  77. USWB 1957, p. 525

Sources
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