Using cars to gauge tornado strength

In the 1996 blockbuster Twister, a semi-articulated fuel truck is lofted and flung by a writhing tornado into the path of the movie’s storm-chasing heroes. Doubtless the filmmakers conceived the scene to demonstrate the fake tornado’s terrible strength, but as a new study concludes, the movement of vehicles can actually be used to evaluate the strength of real tornadoes. Marius Paulikas and Thomas Schmidlin of Kent State University and Timothy Marshall of Haag Engineering examined field surveys of 959 passenger vehicles struck by tornadoes in 1994–2008. After classifying the vehicles according to whether they had been unmoved, displaced, rolled, or lofted, the researchers correlated the movements with the tornadoes’ strength as determined by the damage inflicted on houses, trees, and other structures. For category EF3 and EF4 tornadoes, whose 136–200 mph winds can knock over trains and destroy entire stories of houses, 63% of cars were displaced, with 15% rolled or lofted. But for EF1 and EF2 tornadoes, whose 86–135 mph winds can upturn mobile homes and uproot trees, 65% of cars were not moved at all. Currently, wind’s impact on cars is not taken into account when assigning an EF category to a tornado. Paulikas, Schmidlin, and Marshall’s study suggests that including cars could improve the scale’s accuracy, especially in the absence of buildings and trees. It also suggests that cars could be safer havens than mobile homes. (M. J. Paulikas, T. W. Schmidlin, T. P. Marshall, Weather Climate Soc. 8, 85, 2016, doi:10.1175/WCAS-D-15-0051.1 .)