A storyline-based ICON experiment to assess the role of sea surface temperature anomalies in Storm Boris, a high-impact Central European cyclone

High-impact mid-latitude cyclones affecting Central Europe are shaped not only by synoptic-scale circulation but also by thermodynamic boundary conditions, including sea surface temperature (SST) anomalies that influence moisture availability and storm intensity. Understanding the sensitivity of such events to SST conditions is important for interpreting recent extreme weather events in a warming climate. Here, we apply a storyline-based modelling framework to investigate the role of SST anomalies in Storm Boris, a severe cyclone that affected Central Europe, including Vienna, in September 2024. Convection-permitting simulations are performed with the ICON model at 3 km horizontal resolution over the EURO-CORDEX domain for a one-month period encompassing the event, with the atmospheric initial and lateral boundary conditions provided by the ERA5 reanalysis. A control simulation is driven by observed 2024 boundary conditions, while a sensitivity experiment replaces all SSTs with a 1981–2010 climatological mean, thereby removing the influence of SST anomalies while preserving the large-scale atmospheric circulation associated with the cyclone. By comparing these simulations, we examine how SST anomalies affect cyclone development, moisture transport, precipitation intensity, and storm structure over Central Europe. Rather than providing a probabilistic attribution, this storyline approach explores physically plausible alternative realization of the same circulation pattern under different SST state. While simulations and analyses are ongoing, this contribution presents initial results and methodological insights into the application of convection-permitting storyline experiments to assess the thermodynamic sensitivity of extreme mid-latitude cyclones, with implications for understanding high-impact European weather events.