Meso-NH forecasts of an isolated storm observed during the COPS experiment

On the 15th of July, in a very warm but also very dry environment, an isolated short-lived deep convective storm developed over the Black Forest in the late afternoon. Very few of the high-resolution D-PHASE models were able to capture this event.

Based on various Meso-NH simulations initialized with the ECMWF analysis, the conditions leading to the development of the storm have been studied. Although the modeled storm tends to first appear 10 km more south than the observed one, it is clear that the triggering and propagation of the storm are strongly controlled by the presence of a low-level convergence line, roughly south-north oriented and located along the eastern slopes of the Black Forest massif.

The model results show a limited sensitivity to the microphysical scheme and to a less extent to the model resolution but exhibit significant discrepancies when the initial conditions are modified. In particular, the ARPEGE analysis driven simulations over predict the convective activity.