A 12 hour simulation of the convective line of the MAP IOP2a has been performed with Meso-NH, using a threefold two-way nesting technique with horizontal mesh-sizes of 32, 8 and 2km. The reference experiment based upon the standard Meso-NH microphysical explicit scheme succeeds reasonably well to initiate the convective line over the Alpine foothills and to reproduce its propagation towards the East.

The sensitivity of these results to the microphysical sheme is then explored by comparing with a simulation based upon the prediction of four ice species (including the hail). Results show that a dedicated treatment of hail-like hydrometeores increases the precipitation amount and sustains the convective activity. The microphysical fields of the simulated system are also compared with those derived from the observations of the polarimetric Doppler radar S-Pol.