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On April 19–21, 1920, a multi-day severe weather event affected the Southeastern United States. The most intense portion of the outbreak occurred on the morning of April 20. At least seven tornadoes affected the American U.S. states of Mississippi, Alabama, and Tennessee, six of them rated violent F4s on the Fujita scale. The tornado outbreak killed at least 243 people.

Five of the tornadoes were long tracked, each traveling more than 32 miles (51 km) across Mississippi and into Alabama. A tornado that began in Oktibbeha County, Mississippi, crossed into Alabama and lifted over Limestone County, having covered a distance of more than 130 mi (210 km). Along its path, the tornado destroyed entire communities and killed at least 44 people in Alabama, becoming the state's deadliest tornado until March 21, 1932, when another F4 tornado killed 49 people. An EF5 tornado on April 27, 2011, is currently the state's deadliest on record, with 72 fatalities.

In addition to the tornadoes on April 20, other tornadoes associated with the same weather system occurred on April 19 and April 21.

Background

Toward the end of the period from April 10–20, 1920, a broad trough extended from the Rocky Mountains to the Great Plains, producing inclement weather. At 7:00 a.m. EST (13:00 UTC) on April 20, observations from local stations indicated a low-pressure area of at most 29.6 inches of mercury (1,002 mb) over the Lower Mississippi River near Memphis, Tennessee. A counterclockwise circulation was evident on the daily weather maps, with a trailing cold front approaching Mississippi from the west. An influx of warm, moist air from the Gulf of Mexico yielded surface temperatures of 70° F or greater as far north as Nashville, with mid to upper 70s over the southern halves of Mississippi and Alabama. Conditions were described as being "cloudy and sultry", even during the preceding night, with little fluctuation in relative humidity. Due to a steep temperature gradient and low-level moisture, atmospheric instability was conducive for convective growth, with a convergence zone providing sufficient wind shear for supercells. Relatively colder air above the surface also invaded the warm sector, further heightening parameters for severe thunderstorms. Despite widespread cloud cover, high temperatures in Alabama attained 85 °F or higher at several stations, illustrating the richness of the unstable air mass.

Confirmed tornadoes

April 19 event

April 20 event

April 21 event

Starkville–Cedarbluff–Aberdeen, Mississippi/Bexar–Hackleburg–Phil Campbell–Spruce Pine–Waco–Mehama, Alabama

A destructive, long-lived tornado developed near Bradley, northeast of Sturgis in Oktibbeha County. The funnel rapidly began producing "devastating" damage as it passed northwest of Starkville, with seven dead. Moving northeast, the tornado killed 10 more people near Cedarbluff in Clay County, leveling many homes. Its path was then 200 to 300 yd (600 to 900 ft) wide. Thereafter, the tornado entered Monroe County and proceeded to ravage the western part of Aberdeen. 22 people died there, though it was the only sizable town in the path. Widening to at least 1⁄4 mile (440 yd) wide, the tornado killed five more people in the county before crossing Itawamba County and then moving into Marion County, Alabama. In all, the tornado flattened more than 200 homes, mostly small, in Mississippi.

In Alabama, it leveled entire farms south of Bexar, with nine deaths. One farm alone reported 500 hogs killed. In Marion County alone, the 1⁄2-mile-wide (0.80 km) tornado killed 20 people and injured about 200, leveling 87 homes and damaging 100, especially in the Hackleburg area. In one area, a Ford automobile was hurled 1⁄4 mi (0.40 km), and a swath up to 1+1⁄2 mi (2.4 km) wide was reportedly "swept clean" as homes vanished. In Franklin County, the tornado continued to destroy homes near Phil Campbell and Spruce Pine, but most of the deaths were near the Waco quarry, east of Russellville, where small homes were said to have been "wiped out" and swept away. 19 people died in and near the quarry, nine of whom were part of a family. Nearby, large oak trees were wrested from the earth, huge stones thrown "like a feather", and half of a large boulder transported to Littleville, about 11 mi (18 km) away.

Continuing into southeast Colbert County, the tornado flattened the Mehama community south of Leighton. There, four people died, many homes were destroyed, and numerous cattle were killed; notably, a Ford vehicle, hurled some distance, was stripped of its wheel casings. One other home was destroyed nearby at Wolf Springs. Afterward, the tornado lost intensity, after having maintained F4 or greater strength for more than 100 mi (160 km). Southeast of Town Creek, the tornado killed one more person before losing detection near the Tennessee River; the termination of its path is unknown and may have been in Limestone County, Alabama, or southern Tennessee. Pronounced darkness occurred at several locations in the path of the storm; one observer near Waco noted that there was no daylight and conditions were "dark as midnight."

See also

• List of North American tornadoes and tornado outbreaks
• 2011 Hackleburg–Phil Campbell tornado

Notes

1. All losses are in 1920 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.
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. While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007, Canada utilized the old scale until April 1, 2013; nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.
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. Most countries only recorded tornadoes that produced severe damage or loss of life. 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.
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.

References

1. Grazulis, Thomas P.; Grazulis, Doris. "The Most "Important" US Tornadoes by State". The Tornado Project Online. The Tornado Project. Archived from the original on 14 May 2008. Retrieved 23 February 2016.
2. 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.
3. Grazulis 1993, p. 141.
4. Grazulis 2001a, p. 131.
5. 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.
6. "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.
7. "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on 5 March 2016. Retrieved 25 February 2016.
8. Grazulis 2001a, pp. 251–4.
9. 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.
10. Cook, A. R.; Schaefer, J. T. (August 2008). Written at Norman, Oklahoma. "The Relation of El Niño–Southern Oscillation (ENSO) to Winter Tornado Outbreaks". Monthly Weather Review. 136 (8). Boston: American Meteorological Society: 3135. Bibcode:2008MWRv..136.3121C. doi:10.1175/2007MWR2171.1.
11. Day, P. C. (April 1920). "The Weather Elements" (PDF). Monthly Weather Review. 48 (4): 231–232. Bibcode:1920MWRv...48..231D. doi:10.1175/1520-0493(1920)48<231:TWE>2.0.CO;2. Retrieved 31 January 2016.
12. ^ Smyth, P. H. (April 1920). "The Tornadoes of April 20, 1920, in Alabama" (PDF). Monthly Weather Review. 48 (4): 205–210. Bibcode:1920MWRv...48..205S. doi:10.1175/1520-0493(1920)48<205:TTOAIA>2.0.CO;2. Retrieved 31 January 2016.
13. ^ Jaqua, J. H. (April 1920). "Tornadoes in Eastern Mississippi, April 20, 1920" (PDF). Monthly Weather Review. 48 (4): 203–205. Bibcode:1920MWRv...48..203J. doi:10.1175/1520-0493(1920)48<203b:TIEMA>2.0.CO;2. Retrieved 31 January 2016.
14. Brooks, Harold E. (April 2004). "On the Relationship of Tornado Path Length and Width to Intensity". Weather and Forecasting. 19 (2). Boston: American Meteorological Society: 310. Bibcode:2004WtFor..19..310B. doi:10.1175/1520-0434(2004)019<0310:OTROTP>2.0.CO;2.
15. ^ Grazulis 1993, pp. 769–770
16. Cole, Harvey S. (April 1920). "General Summary". Climatological Data: Arkansas Section. 25: 27–30.
17. Grazulis 1993, p. 56

Sources

• Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. ISBN 1-879362-03-1.
• Grazulis, Thomas P. (2001a). The Tornado: Nature's Ultimate Windstorm. Norman: University of Oklahoma Press. ISBN 978-0-8061-3538-0.
• Grazulis, Thomas P. (2001b). F5-F6 Tornadoes. St. Johnsbury, Vermont: The Tornado Project of Environmental Films.

• F4 tornadoes by date
• 20th-century tornadoes
• 1920 meteorology
• Tornadoes in Mississippi
• Tornadoes in Alabama
• 1920 natural disasters in the United States
• 1920 in Alabama
• 1920 in Mississippi
• April 1920 events in the United States