This is because they are too small to be affected by the Coriolis force - the way the Earth's rotation deflects winds around high and low pressure areas. However anticlockwise tornadoes are more prevalent in the northern hemisphere because some tornadoes develop from a larger circulation in a thunderstorm which can be affected by the Coriolis force. It was the largest outbreak in US history, leaving 330 dead and 5,000 injured. Many sources report 148 tornadoes, although Dr. Fujita, a leading Amerian tornado researcher, reclassified 4 as microbursts - strong and damaging winds which descend from a thunderstorm. However it is possible that more than one tornado was involved.
Tornadoes can change direction suddenly and can outrun vehicles.
One of Britain's two most severe tornadoes destroyed the church of St. Mary le Bow and 600 homes in central London on 23 October 1091. Four of the church's 26-foot long rafters were reportedly driven so hard into the ground that only four feet of them was visible. The other candidate for the UK's most intense tornado occurred on 12 September 1810, when one rated T8 on the Tornado Intensity Scale travelled from Old Portsmouth to Southsea Common. The Tay Bridge rail disaster in Scotland, on 28 December 1879 and immortalised in verse by William McGonagall, was caused by waterspouts. Eyewitnesses saw two or three close to the bridge, immediately before seeing the glowing embers from the engine fall into the River Tay, which are believed to have cut the bridge after the pre-existing high winds and poor construction weakened it.