Tornado outbreak of May 7–9, 1927

On May 7–9, 1927, a deadly and destructive tornado outbreak affected the Midwestern and Southern United States, producing numerous strong tornadoes that killed 217 or more people. The strongest tornado of the outbreak, retroactively rated F5 on the Fujita scale, was a long-tracked tornado family that killed 10 people in southern Kansas on May 7. The deadliest tornado of the outbreak hit Poplar Bluff, Missouri, on May 9, doing F4 damage and killing at least 98 people. Other F4s that day collectively killed 75 people in Texas and Arkansas; a pair of F3s in the latter state killed 20. A few F4s in Missouri on May 8 also claimed 10 lives. According to tornado historian Thomas P. Grazulis, May 9, 1927, was "among the worst tornado days in U.S. history", featuring nine tornadoes that killed at least five people.

Confirmed tornadoes

Prior to 1990, there is a likely undercount of tornadoes, particularly E/F0–1, with reports of weaker tornadoes becoming more common as population increased. A sharp increase in the annual average E/F0–1 count by approximately 200 tornadoes was noted upon the implementation of NEXRAD Doppler weather radar in 1990–1991. 1974 marked the first year where significant tornado counts became homogenous with contemporary values, attributed to the consistent implementation of Fujita scale assessments. Numerous discrepancies on the details of tornadoes in this outbreak exist between sources. The total count of tornadoes and ratings differs from various agencies accordingly. The list below documents information from the most contemporary official sources alongside assessments from Grazulis.