This study presents the detailed analysis of a novel and first-of-its-kind 10-year multi-model ensemble of kilometer-scale convection-permitting climate model (CPM) simulations over the Greater Alpine Region. The simulations were obtained by downscaling global climate model (GCM) projections using regional climate models (RCMs) and further downscaling to the kilometer scale using convection-permitting climate models (CPMs) . This study evaluates the CPMs and assesses their added value with respect to RCMs regarding basic and heavy precipitation characteristics. In addition, this study assesses projected changes for the end of the century. The analysis is performed for climatological seasons, for different temporal aggregations between 1 hour and 5 days, and for various precipitation indices.. ERA-Interim-driven and historical GCM-driven CPM simulations are compared against daily and hourly observational datasets, as well as their driving RCM counterparts to evaluate their performance and added value. Evaluation reveals that CPMs refine spatial patterns, reduce the overestimation of precipitation frequency and better capture intense precipitation characteristics, especially on the sub-daily scale and in summer. Climate change projections show an intensification of precipitation for all seasons and across all temporal aggregation levels. During summer, mean precipitation and precipitation frequency are projected to decrease, especially in the Mediterranean. In winter, an increase is projected across most parts of the Alps. CPMs and RCMs show agreement, with CPMs indicating slightly amplified signals and reduced model spread. The findings are consistent with previous studies using individual simulations, but provide one of the first multi-model assessment of projections in heavy precipitation over the Alps.

Hail is a significant convective weather hazard, often causing considerable crop and property damage across the world. Although extremely damaging, hail still remains a challenging phenomenon to model and forecast, given the limited computational resolution and the gaps in understanding the processes involved in hail formation. Here, eight hailstorms occurring over the Alpine-Adriatic region are analyzed using Weather Research and Forecasting (WRF) and Consortium for Small Scale Modeling (COSMO) simulations, with embedded HAILCAST and Lightning Potential Index (LPI) diagnostics at kilometer-scale grid spacing (~2.2 km). In addition, a model intercomparison study is performed to investigate the ability of the different modeling systems in reproducing such convective extremes, and to further assess the uncertainties associated with simulations of such localized phenomena. The results are verified by hailpad observations over Croatia, radar estimates of hail over Switzerland and lightning measurements from the LINET network. The analysis revealed that both HAILCAST and LPI are able to reproduce the areas and intensities affected by hail and lightning. Moreover, the hail and lightning fields produced by both models are similar, although a slight tendency of WRF to produce smaller hail swaths with larger hailstones and higher LPI compared to COSMO is visible. It is found that these differences can be explained by systematic differences in vertical profiles of microphysical properties and updraft strength between the models. Overall, the promising results indicate that both HAILCAST and LPI could be valuable tools for real-time forecasting and climatological assessment of hail and lightning in current and changing climates.