Genesis of mesoscale convective systems above uneven soil moisture conditions

The sensitivity of a simulation of the genesis of a mesoscale convective system to the initial soil moisture distribution was examined. In the initialization of this cloud-resolving simulation, antecedent precipitation was used to make the soil moisture distribution heterogeneous. Generally, the experiments produced qualitatively similar results, producing a quasicircular cloud shield, indicating the importance of large-scale dynamics. However, the soil moisture distribution affected where convection was likely to occur. For the case examined, a wet soil moisture anomaly suppressed convection, but convection preferentially occurred on the periphery of the wet soil moisture anomalies due to the mesoscale circulations there. Sensitivity experiments also showed that soil moisture with grid spacing of 40 km may be adequate to initialize a cloud-resolving model for MCS simulations.