It has been 47 years since the April 1974, “Super Outbreak” of tornadoes; the outbreak changed severe weather forecasting more than any other. Within 18 hours from April 3 to April 4, 1974, around 150 tornadoes tore their way through 13 states plus eastern Ontario, killing 330 people and injuring more than 6,000. It was as if the weather was organized into a killing machine with families of tornadoes coming in wave after wave.
The storms traumatized the eastern United States, but also led to great improvements in tornado spotter networks, safety procedures in schools and businesses and tornado siren systems. It also inspired a great deal of tornado research which led to many improvements in forecasting. The Super Outbreak was unparalleled in the modern era until another super outbreak swept across the Deep South over four days in April of 2011, killing 315 people. A month later, more than 160 were killed in an EF-5 tornado in Joplin, Mo.