Some aspects of the international climatology of tornadoes by damage classification

Reports of tornadoes, broken down by damage, from seven countries have been examined. In particular, the long-term relatively high-quality dataset from the US is used to develop distributions which indicate that the number of tornadoes decreases log-linearly with increasing F-scale. Two distinct distributions, one apparently associated with supercell tornadogenesis processes and the other with non-supercell processes, are found in both the US data and in other countries. The similarity of the distribution in the US prior to the 1950s, when an official, organized collection effort began, and the French record, suggests that only 15% of French tornadoes are being reported currently. In addition, we can use the simple statistical distributions to estimate the return period of violent tornadoes in France (approximately one every 5–10 years) and the UK (approximately one every 250–300 years).