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From May 20–22, 1949, a large-scale tornado outbreak affected portions of the continental United States, killing several dozen people and injuring hundreds more. Generating at least 66 tornadoes, the severe weather event produced 51 or more significant—F2 or stronger—tornadoes, half a dozen of which were retroactively rated F4 by tornado expert Thomas P. Grazulis. One of the largest on record prior to the start of official data in 1950, the outbreak included many tornado families and unrecorded or weak tornadoes, so its actual total was likely considerably higher than noted here. Newspaper headlines mentioned an "army" of tornadoes in Kansas on May 20. More than 100 tornadoes in all, mainly weak, may have formed over the Great Plains that day; Grazulis was able to find 40 just in Kansas "with little effort".
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 (E/F2+) 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 tornado historian Thomas P. Grazulis.
Notes.
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References.
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