1984 Soviet Union tornado outbreak

The 1984 Soviet Union tornado outbreak, also known as the 1984 Ivanovo tornado outbreak, was one of only three disastrous tornado outbreaks in modern Russian history (one of the others being the 1904 Moscow tornado) 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 F5 in intensity on the Fujita scale, based upon observed damages. The deadliest single tornado was posthumously rated at F5 intensity and killed at least 92 people along its long path near Ivanovo and other towns. The tornado, up to 800 metres (0.50 mi) wide, caused extreme damage, reportedly annihilating steel-reinforced concrete structures and throwing heavy objects of 320,000 kilograms (710,000 lb) for distances up to 200 metres (0.12 mi). Another tornado, assessed to have been at least F4 and possibly F5 in intensity, 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 400 people and injured 213.

Meteorological synopsis

On June 8, 1984, a negatively tilted trough caused an extratropical low pressure area to form over the coast of the Romanian People's Republic (now non-Communist Romania). Surface moisture moved north from the Black Sea and caused nearby dew points to rise to 20 °C (68 °F); though at that time these were restricted to Romania and the Ukrainian SSR, dew points were higher than average elsewhere.^[1] 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 (now Belarus), 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-scale lifting 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.^[1]

Tornadoes

• Three of the tornadoes were never rated

June 9 event

Notable tornadoes

Ivanovo/Lunevo

A large, long-tracked, and devastating tornado, considered one of the worst in Russian history, destroyed numerous towns along its path. Rated F5 on the Fujita scale, the half-mile-wide (800-m)^[4] tornado killed at least 92 people and injured more than 130 others. Several reinforced structures were completely destroyed, and about 1,180 homes were also leveled by the tornado.^[5] Some estimates indicate up to 95 deaths^[2] or even more, with some sources suggesting all 400 deaths in the outbreak were related to the Ivanovo tornado.^[1]

At 1130 UTC^[1]—other sources say 1205 UTC^[5]—this powerful multiple vortex tornado touched down 15 mi (24 km) south of Ivanovo.^[3] Near Ivanovo, the tornado snapped or bent pine, spruce, and birch trees about 1 m (3.3 ft)–3 m (9.8 ft) from ground level.^[3] In the town itself, the tornado picked up a crane, weighing 320,000 kilograms (710,000 lb), and threw it 200 metres (0.12 mi).^[1][6] The tornado reportedly swept away large industrial buildings^[5] and steel-reinforced concrete structures, leaving little or no debris on the foundations.^[4][7] Numerous vehicles and heavy objects were thrown very long distances as well.^[4] The tornado also tore asphalt from a highway near Ivanovo.^[6]

Near the Volga River, the tornado ripped up trees by their roots and destroyed many small huts. It also carried a water tank weighing 50 tonnes (110,000 lb) for 200 yd (0.11 mi).^[6] Steel water containers capable of holding 150 cubic metres (40,000 US gal) of water were carried 100 metres (330 ft) in the air and transported 1 km (0.62 mi) from their original site. Hail in association with the parent thunderstorm weighed up to 1 kilogram (2.2 lb), among the heaviest hailstones measured anywhere in the world;^[1] though the measurement came with few details, it is comparable to the world record, a hailstone also measuring 1 kg (2.2 lb) in Bangladesh on April 15, 1986.^[8] The F5 tornado tracked for 99 miles (160 km)—though some sources suggest only 80 kilometres (50 mi)^[1]—before dissipating near Lunevo in Yaroslavl Oblast. It caused at least 92 deaths, though many others likely went unreported.^[4]

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.^[4] However, recent research indicates that the Ivanovo storm was not the same as the one that produced the Kostroma tornado.^[1] Numerous trees were thrown long distances by the tornado. A crane weighing 350 t (770,000 lb) was knocked over, several bridges were destroyed, 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.^[4]

See also

• List of F5 and EF5 tornadoes

References

External links

• http://islandnet.com/~see/weather/storm/tornadoes-europe.htm