Heavy precipitation over Italy during HyMeX IOP13: numerical investigation using two mesoscale models

During IOP13 of the HyMeX SOP1, heavy precipitation affected the hydro-meteorological sites over Italy. The outbreak of the Mistral in the Mediterranean basin, associated with the passage of an organized frontal system, produced favourable large-scale conditions for convection development. In particular, convective activity was triggered in areas characterized by mesoscale low-level convergence or strong orographic forcing. Two high-resolution NWP models were employed in a synergistic way in order to study relevant physical aspects responsible for the development of convective systems. Several experiments performed with COSMO and MOLOCH models, using different grid spacing and modified orography allows to identify different phases of the event characterized by different forcing mechanisms. In particular, the differences in the location and timing of convection between the simulations and comparisons against available observations are used to identify and explore the processes that need to be well represented in order to reproduce adequately the mechanisms initiating heavy precipitation.