Half a century ago, a super tornado outbreak led to meteorological innovation
April 3, 1974, is known as the "Day of the Killer Tornadoes" -- but it was also a turning point for severe weather forecasting across the weather enterprise.
By
Kevin Byrne, AccuWeather senior editor
Published Apr 3, 2020 7:30 PM EST
In just under 24 hours, 148 tornadoes caused 315 fatalities and injured over 5,000 people across 13 states. Known as the Super Outbreak, this event set the precedent for tornado research and forecasts.
Fifty years ago next week, Americans from the Great Lakes to the Deep South found themselves under assault from a multi-day barrage of tornadoes that would not only go down as one of the worst tornado outbreaks in U.S. history but also a crucial turning point in the field of meteorology.
The dates April 3-4, 1974, will live in infamy as nearly 150 tornadoes ripped through 13 states in one day. In the horrifying aftermath, 315 people were found dead, and over 5,400 were injured. Amid the onslaught of severe storms, as many as 15 tornadoes were wreaking havoc simultaneously.
A total of seven F5-strength tornadoes were confirmed, the most on record for one day or from any outbreak. Only the 2011 Super Tornado Outbreak from April 25-28 produced more tornadoes in a 24-hour period. The Easter 2020 tornado outbreak and the March 31, 2023 tornado outbreak came close to, but did not exceed, the count of 148 tornadoes from the 1974 Super Outbreak, with 141 and 147 twisters, respectively.
A 1978 documentary produced by the federal government's former Office of Civil Defense showed extensive footage of the storms and the carnage they left behind. The documentary referred to April 3 as the Day of the Killer Tornadoes.
The Ohio Valley was one of the hardest hit locations, with two violent F5 tornadoes ravaging the Ohio towns of Xenia and Sayler Park. According to the National Weather Service, the Xenia tornado was the deadliest of the entire outbreak. Thirty-four people lost their lives as the twister flattened entire neighborhoods.
Brandenburg, Kentucky, was another town that was devastated. More than 120 homes were obliterated by a monster 2,400-foot-wide F5 tornado, which left 28 people dead in the small town.
Three F5 tornadoes tore through northern Alabama. The first twister that struck Franklin County near Newburg, Alabama, was described in National Weather Service warnings as "big and powerful and taking everything in its path."
The ground was impaled by a bathtub at this spot in Harvest. (NWS-Huntsville, Alabama/Madison County EMA)
NWS-Huntsville, Alabama/Madison County EMA
AccuWeather Senior Meteorologist Dan Kottlowski lived through the outbreak while attending college at Purdue University in West Lafayette, Indiana. Kottlowski, who has worked at AccuWeather for nearly 50 years forecasting many types of severe and tropical weather, said the atmospheric ingredients in place that day were very typical of a setup for a severe weather outbreak.
Warm, moist air was moving up from the Gulf of Mexico, ahead of a very impressive storm in the central U.S., Kottlowski explained. At the same time, cold air aloft was wrapping around the back side of the storm, over-topping the warm, moist air and creating instability.
Tracks of all 148 tornadoes that touched down on April 3-4, 1974, during the Super Tornado Outbreak.
"Aloft, the air spread out in a fan-shaped pattern causing the mid- and upper-levels of the atmosphere to lift at a faster rate than normal, causing the air east and along and ahead of the advancing cold front to be vented very effectively like a large chimney," Kottlowski said. "The contrast at the surface combined with the enhanced lift aloft led to dramatic thunderstorm development."
Several scientists throughout the weather industry used the outbreak as a springboard to learn more about tornadoes. Among them was Dr. Ted Fujita, a researcher from the University of Chicago, who would closely examine every tornado from the two-day stretch. Several years earlier in 1971, Fujita created the Fujita Scale, a six-point measurement system that became the international standard for rating tornadoes based on intensity and area, until it was later modified in 2007 to the Enhanced Fujita Scale.
This outbreak served as an opportunity for Fujita to put his scale into use by cataloging and gathering information about the twisters, according to AccuWeather Certified Consulting Meteorologist Steve Wistar, who was just finishing his meteorological studies in college at the time.
"What stands out for me in addition to it being a ‘black swan’ event in the atmosphere is [the tornado outbreak] offered the opportunity for Ted Fujita, perhaps the single most creative, inventive, insightful meteorologist in my lifespan, to further refine his theories about the way severe weather comes about," said Wistar, another AccuWeather veteran who has been with the company for 43 years.
In 1974, NWS offices were not all equipped with radar, and forecasters at certain offices that did have access to radar would need to trace storms from the screens onto thin paper maps to determine location and movement. In addition, meteorologists would lean heavily on identifying “hook echoes” and storm spotters' reports to issue tornado warnings.
National Weather Service WSR-57 weather radar out of Columbus, Ohio, shows the Xenia, Ohio supercell thunderstorm and hook echo, where the tornado was occurring on Apr 4, 1974. (NWS/NCDC)
NWS/NCDC
Kottlowski said in the aftermath that there was a major push to conduct extensive research through government-funded university field programs to understand severe weather and tornado development.
“This led to the development of better diagnostic tools such as Doppler radar, mesoscale computer models, and advanced techniques to diagnose severe weather potential through satellite imagery,” he said.
Kottlowski added that the development of faster computers and better mesoscale observational data enabled this research to succeed. With a better understanding of the atmosphere and more advanced tools at their disposal, forecasters then had greater lead times to warn citizens of tornado danger as well as educate them on how to mitigate severe weather risks.
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News / Severe Weather
Half a century ago, a super tornado outbreak led to meteorological innovation
April 3, 1974, is known as the "Day of the Killer Tornadoes" -- but it was also a turning point for severe weather forecasting across the weather enterprise.
By Kevin Byrne, AccuWeather senior editor
Published Apr 3, 2020 7:30 PM EST
In just under 24 hours, 148 tornadoes caused 315 fatalities and injured over 5,000 people across 13 states. Known as the Super Outbreak, this event set the precedent for tornado research and forecasts.
Fifty years ago next week, Americans from the Great Lakes to the Deep South found themselves under assault from a multi-day barrage of tornadoes that would not only go down as one of the worst tornado outbreaks in U.S. history but also a crucial turning point in the field of meteorology.
The dates April 3-4, 1974, will live in infamy as nearly 150 tornadoes ripped through 13 states in one day. In the horrifying aftermath, 315 people were found dead, and over 5,400 were injured. Amid the onslaught of severe storms, as many as 15 tornadoes were wreaking havoc simultaneously.
Photo Gallery: The 1974 Super Tornado Outbreak
A total of seven F5-strength tornadoes were confirmed, the most on record for one day or from any outbreak. Only the 2011 Super Tornado Outbreak from April 25-28 produced more tornadoes in a 24-hour period. The Easter 2020 tornado outbreak and the March 31, 2023 tornado outbreak came close to, but did not exceed, the count of 148 tornadoes from the 1974 Super Outbreak, with 141 and 147 twisters, respectively.
A 1978 documentary produced by the federal government's former Office of Civil Defense showed extensive footage of the storms and the carnage they left behind. The documentary referred to April 3 as the Day of the Killer Tornadoes.
The Ohio Valley was one of the hardest hit locations, with two violent F5 tornadoes ravaging the Ohio towns of Xenia and Sayler Park. According to the National Weather Service, the Xenia tornado was the deadliest of the entire outbreak. Thirty-four people lost their lives as the twister flattened entire neighborhoods.
Brandenburg, Kentucky, was another town that was devastated. More than 120 homes were obliterated by a monster 2,400-foot-wide F5 tornado, which left 28 people dead in the small town.
Three F5 tornadoes tore through northern Alabama. The first twister that struck Franklin County near Newburg, Alabama, was described in National Weather Service warnings as "big and powerful and taking everything in its path."
The ground was impaled by a bathtub at this spot in Harvest. (NWS-Huntsville, Alabama/Madison County EMA)
AccuWeather Senior Meteorologist Dan Kottlowski lived through the outbreak while attending college at Purdue University in West Lafayette, Indiana. Kottlowski, who has worked at AccuWeather for nearly 50 years forecasting many types of severe and tropical weather, said the atmospheric ingredients in place that day were very typical of a setup for a severe weather outbreak.
Warm, moist air was moving up from the Gulf of Mexico, ahead of a very impressive storm in the central U.S., Kottlowski explained. At the same time, cold air aloft was wrapping around the back side of the storm, over-topping the warm, moist air and creating instability.
Tracks of all 148 tornadoes that touched down on April 3-4, 1974, during the Super Tornado Outbreak.
"Aloft, the air spread out in a fan-shaped pattern causing the mid- and upper-levels of the atmosphere to lift at a faster rate than normal, causing the air east and along and ahead of the advancing cold front to be vented very effectively like a large chimney," Kottlowski said. "The contrast at the surface combined with the enhanced lift aloft led to dramatic thunderstorm development."
Several scientists throughout the weather industry used the outbreak as a springboard to learn more about tornadoes. Among them was Dr. Ted Fujita, a researcher from the University of Chicago, who would closely examine every tornado from the two-day stretch. Several years earlier in 1971, Fujita created the Fujita Scale, a six-point measurement system that became the international standard for rating tornadoes based on intensity and area, until it was later modified in 2007 to the Enhanced Fujita Scale.
This outbreak served as an opportunity for Fujita to put his scale into use by cataloging and gathering information about the twisters, according to AccuWeather Certified Consulting Meteorologist Steve Wistar, who was just finishing his meteorological studies in college at the time.
"What stands out for me in addition to it being a ‘black swan’ event in the atmosphere is [the tornado outbreak] offered the opportunity for Ted Fujita, perhaps the single most creative, inventive, insightful meteorologist in my lifespan, to further refine his theories about the way severe weather comes about," said Wistar, another AccuWeather veteran who has been with the company for 43 years.
In 1974, NWS offices were not all equipped with radar, and forecasters at certain offices that did have access to radar would need to trace storms from the screens onto thin paper maps to determine location and movement. In addition, meteorologists would lean heavily on identifying “hook echoes” and storm spotters' reports to issue tornado warnings.
National Weather Service WSR-57 weather radar out of Columbus, Ohio, shows the Xenia, Ohio supercell thunderstorm and hook echo, where the tornado was occurring on Apr 4, 1974. (NWS/NCDC)
Kottlowski said in the aftermath that there was a major push to conduct extensive research through government-funded university field programs to understand severe weather and tornado development.
“This led to the development of better diagnostic tools such as Doppler radar, mesoscale computer models, and advanced techniques to diagnose severe weather potential through satellite imagery,” he said.
Kottlowski added that the development of faster computers and better mesoscale observational data enabled this research to succeed. With a better understanding of the atmosphere and more advanced tools at their disposal, forecasters then had greater lead times to warn citizens of tornado danger as well as educate them on how to mitigate severe weather risks.
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