Analysis of significant tornado events in Central Europe: synoptic situation and convective development

Abstract

Tornadic storms with a tornado intensity of F2 or stronger on the Fujita scale that occurred in recent years (between 2013 and 2020) in Germany were analysed in detail. The 20 tornadoes, which developed on 17 different days, occurred in various parts of Germany. The majority of the analysed tornadoes occurred from May to early September. The other four events are typical cold-season cases that differ from the warm-season cases in some aspects which are discussed where applicable. Similarities and differences of the prevailing synoptic and mesoscale conditions are assessed in addition to the convective environment of the events. On the majority of the analysed tornadic days, the event happened on the forward flank of a long wave trough that was slowly propagating eastward. The second typical situation is a short wave trough passing rather fast over the area of interest from West to East. All cold-season cases occurred in high shear, low CAPE environments. Furthermore, the type of convection is analysed using a multi-source approach to best characterise the events. For this purpose, radar reflectivity and rotation data were combined with lightning detection in order to analyse the tornadic storms with respect to storm mode and storm evolution as well as lightning and rotation characteristics. The most common convective mode is linearly organised convection followd by multicellular storms. In many of the warm-season cases, radar radial wind data showed a persistent rotation track. The lightning activity of the warm-season season tornadic storms was high. In many cases, a lightning jump occurred between 5 and 120 minutes before the event.

Keywords

• tornado
• synoptic pattern
• convective environment
• multi-sensor
• mesocyclone
• lightning jump