The 1984 Soviet Uniontornado outbreak, also known as the 1984 Ivanovotornado outbreak, was one of only three disastrous tornado outbreaks in modern Russian history and the third-deadliest tornado outbreak in European history. Occurring on June 9, 1984, the outbreak 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, based upon observed damages. The main tornado, an F4, which was up to wide, caused extreme damage, throwing heavy objects of for distances up to. Another tornado, assessed to have been at least F4, occurred at Kostroma. Severe thunderstorms also produced hail up to in weight, among the heaviest hailstones confirmed worldwide. In all, the entire tornado outbreak killed at least 69 people and injured 804.
Meteorological synopsis
On June 8, 1984, a negatively tilted trough caused an extratropicallow pressure area to form over the coast of the Socialist Republic of Romania. Surface moisture moved north from the Black Sea and caused nearby dew points to rise to ; though at that time these were restricted to Romania and the Ukrainian SSR, dew points were higher than average elsewhere. By 1800 UTC, developing thunderstorms over the Ukrainian SSR spread overnight into the Russian SFSR. Between 00 and 12 UTC on June 9, the strengthening low pressure area moved north-northeast over the northwestern Russian SFSR before undergoing occlusion. In the meantime, a strong cold front rapidly advanced along a line extending south from the surface low, then south of Minsk in the Byelorussian SSR, to near Bucharest. This front separated the drier air mass to the north from the warm, moist air mass near the Black Sea, and strong wind speeds near ground level caused vertical mixing. Therefore, dew points actually dropped before the first tornadoes formed, but nevertheless several factors overcame the lower dew points to produce tornadoes. Among these were a strong upper-level jet stream, clear skies causing daytime heating and instability, strong synoptic-scalelifting leading to ascension of updrafts, and high adiabatic lapse rates promoting thunderstorm development. All these factors combined to produce severe weather near Moscow. The tornadoes occurred in this region because an unstable and moist air mass, supported by warm sea surface temperatures over the Black Sea, had been in place four days before the outbreak began. The unusually strong intensity of the trough in the region on June 8–9, with a 500-millibar geopotential height measured at about 2.7 standard deviations below normal, also favored an intense tornado outbreak.
Tornadoes
Three of the tornadoes were never rated
June 9 event
Ivanovo/Lunevo
A large, long-tracked, and devastating tornado, considered one of the worst in Russian history, destroyed numerous towns and villages along its path. Rated F4 on the Fujita scale, the 500 metres tornado killed at least 69 people and injured more than 130 others. About 1,180 homes were also damaged, destroyed or leveled by the tornado. Some estimates indicate up to 95 deaths or even more, with some sources suggesting 400 deaths in the outbreak were all related to the Ivanovo tornado. At 1130 UTC—other sources say 1205 UTC—this powerful multiple vortex tornado touched down south of Ivanovo. Near Ivanovo, the tornado snapped or bent pine, spruce, and birch trees about – from ground level. In the town itself, the tornado picked up and cast aside a crane, weighing, and threw a water tank, weighing 50,000 kilograms, over a distance of. ESWD mentions that the tornado destroyed factory areas. Near the Volga River, the tornado :wikt:uprooting|ripped up trees by their roots and destroyed many small huts. It also carried a water tank weighing for. Steel water containers capable of holding of water were carried in the air and transported from their original site. Hail in association with the parent thunderstorm weighed up to, among the heaviest hailstones measured anywhere in the world; though the measurement came with few details, it is comparable to the world record, a hailstone also measuring in Bangladesh on April 15, 1986. The F4 tornado tracked for —though some sources suggest only —before dissipating near Lunevo in Yaroslavl Oblast. It caused at least 92 deaths, though many others likely went unreported.
Kostroma/Lyubim
According to Russian researchers writing in the 1980s, this tornado was either the same as the Ivanovo tornado or a member of the Ivanovo tornado family; if the latter, it may indicate that the Ivanovo tornado was in fact two separate tornadoes spawned by the same thunderstorm. However, recent research indicates that the Ivanovo storm was not the same as the one that produced the Kostroma tornado. Numerous trees were thrown long distances by the tornado. A crane weighing was knocked over, and numerous other structures were damaged. The severity of the damage was rated F4; however, there are indications that the tornado may have attained F5 intensity.
