A Case study - Splitting Supercells over Berlin on July 10, 2020

As known, the presence of vertical wind shear leads to the organization of supercell thunderstorms. Changes in the wind profile can affect isolated convection especially in the development stage and in relation to its behavior.

This study takes a closer look at the organization of storms initiating in an urban environment that can have impacts on public life and infrastructure. Therefore an exemplary weather event over east Germany should be discussed in greater detail. While considering our theoretical and conceptual knowledge about supercelluar convection, it is important to ask further questions about the given atmospheric parameters or the specific time of convective initiation, when covering these events. Also it is essential to be able to make statements about the static stability and the sources of moisture. The local effects of a region, that may have influences on the convective scale, can help us to explain observed short-term changes. Especially the DBZ radar reflectivity, as one of the most common nowcast tools, can provide useful insights into atmospheric dynamics in context to the current flow pattern.

By evaluating NWP model data and using different observations, a summary of the synoptic pattern will be given that set the stage for isolated thunderstorm development over Berlin on this day. With using our understanding of dynamics in relation to the storm scale, the accuracy of nowcasting these cells should be clarified. For this purpose, the concept of the dynamic split and the storm motion as predictive indicators will be applied. Could the convective mode have been estimated already in the forecast process?

The case study can be considered as a useful complement for nowcasting silimar events in the future.