Abstract A conceptual model of the evolution of the severe local storm environment is discussed in conjunction with three case studies drawn from data obtained during the 1979 SESAME field program. The conceptual model describes how a particular configuration of topography and air flow can produce a low-level restraining inversion or “lid” which focuses the location and even enhances the intensity of severe local storms. While capping inversions have often been attributed to subsidence, in this model it is demonstrated that the lid frequently originates from differential advection of a hot, dry mixed layer from an elevated plateau over a cooler, moister layer advected northward ahead of a trough in the westerlies. For either the elevated mixed layer or subsidence inversion, this type of vertical stratification suppresses release of convective instability while, nevertheless, allowing the latent instability of the boundary layer to increase with time. However, for elevated mixed layer lids, the differing s...