1931 Lublin tornado
On July 20, 1931, a violent tornado struck the city of Lublin in the Republic of Poland. The damage from the tornado was rated F4 on the Fujita scale by the European Severe Storms Laboratory. The tornado killed six people and injured at least 100 others.
Summary
The tornado destroyed several buildings in Lublin. Some structures had walls that were thick. Train railroad cars were overturned and some were moved a few meters away. Industrial chimneys were thrown by the tornado. Structures made out of iron were bent. Buildings made of wood in the path of the tornado were leveled to the ground. These included sawmills, homes, and barns. The Lublin slaughterhouse and sugar factory were completely destroyed. Other industrial buildings were destroyed as well. Some buildings had debris thrown over a mile away. A city bus was picked up and thrown by the tornado. The tornado traveled around and was described as being a narrow “dark mass in the shape of a funnel”. In total, the tornado killed six people and injured over 100 others.The Polish Weather Service estimated that the tornado had winds between. This mean it was potentially at F5 intensity, as F5 tornadoes begin with winds at. But in publication by members of staff of the University of Warsaw and Adam Mickiewicz University in Poland as well as the National Oceanic and Atmospheric Administration in the United States doubts were expressed about this assessment: " this estimate is highly uncertain since no typical F5 damage was reported. Instead, F4 damage was plausible".
It is possible that the wind force assessment is overstated due to overly simple assumptions made during calculations. In a scientific article summarizing the events, Romuald Gumiński estimates the minimum pressure force and corresponding dynamic pressure needed to cause two damages - derailment of the train car and breaking of the wall. Based on the mass, track gauge and lateral surface of the car, he estimates that the minimum wind speed needed to overturn the car is 111 m/s, and based on the thickness and height of the building wall, that the minimum wind speed needed to break the wall is 145 m/s. These are values well above the wind speeds expected to cause such damage. A train overturn is a characteristic of an EF3 tornado with winds in the 136-165 mph range. It's Gumiński was the vice-director of the Polish government Meteorological Department.