The influence of horizontally-varying CAPE and vertical shear on numerically-simulated convective storms

Vertical shear and Convective Available Potential Energy (CAPE) are known to play a large role in determining the structure and evolution of severe local storms. Numerical simulations and observational studies both suggest a strong relationship between vertical shear, CAPE and storm morphology. However, the evolution of severe storms is difficult to predict when these quantities vary over the lifetime of a storm system due to its motion through a horizontally inhomogeneous environment. Storms beginning in an environment supportive of multicells may later experience conditions adequate for supercells.

In this study, idealized experiments are conducted in which the steady-state environmental vertical shear and the CAPE are forced to vary at a prescribed rate across a specified domain. Simulations are performed using straight hodographs in both weak and strong shear regimes. In all simulations, vertical shear and CAPE vary simultaneously, with simulated storms compared to previous studies in which the vertical shear and CAPE were varied separately. The influence of these variations in vertical shear and CAPE on storm morphology will be discussed.