Sensitivity of the Great Plains Severe-Storm Environment to Soil-Moisture Distribution

Abstract

This study examines the influence of differences in ground moisture over the southern Great Plairs and the Mexican plateau on the formation and evolution of the dryline, the elevated mixed layer, and the local planetary boundary layer. These features are examined in a series of numerical experiments in which dry and wet surface conditions over the southern plains and Mexico are simulated by the model Results of the numerical simulations show that the dry soil conditions of northern Mexico are critical to the formation of the lid, and the variable soil conditions of the southern Great Plains are important for the processes of differential surface heating and generation of low-level instability through strong surface evaporation. The processes interact dynamically to alter the prestorm conditions and subsequent convective patterns observed over Texas and Oklahoma in the SESAME IV case.