The meteorological environment of significant tornadoes in northern and central Europe

Environmental conditions of 18 tornado cases associated with at least F2 intensity in Finland and Germany have been examined. An attempt was made to classify the cases on the basis of their location with respect to atmospheric features such as frontal boundaries and jet streaks. Surface and upper-air observations have been used, as well as analyses from the global atmospheric model of the European Centre for Medium-Range Weather Forecasts (ECMWF). The question addressed was what made the particular locations favourable for tornado development. In particular, the generation of instability and favourable vertical wind shear by sub-synoptic and mesoscale processes was investigated. Additionally, we evaluated to what extent the ECMWF analyses accurately represent the wind, temperature and moisture fields in the mesoscale environment of the tornadic storms.