1984 Soviet Union tornado outbreak

The 1984 Soviet Union tornado outbreak, also known as the 1984 Ivanovo tornado outbreak, occurred on June 9, that struck the Ivanovo and Yaroslavl regions north of Moscow, an area over 400,000 km². At least two of the eleven known tornadoes were violent events, equal to F4 or higher in intensity on the Fujita scale. It was one of only three disastrous tornado outbreaks (one of the others being the 1904 Moscow tornado) in modern Russian history, and the third-deadliest tornado outbreak in European history.

Based upon observed damages, the main tornado, an F4 in Ivanovo caused extreme damage, throwing heavy objects of 50,000 kilograms (110,000 lb) for distances up to 200 metres (0.12 mi). Another tornado, assessed to have been at least F4, occurred at Kostroma. Severe thunderstorms also produced hail up to 1 kilogram (2.2 lb) in weight, among the heaviest hailstones confirmed worldwide. In all, the entire tornado outbreak killed at least 69 people (though the exact death toll is unknown) and injured 804. It was previously rated as an F5, however, recent reanalysis has lowered the rating to F4 in 2018 by the European Severe Storms Laboratory.