Evaluation of the Evolution of Severe Storm Environments through Use of the Lapse Rate Tendency Equation

Severe Storms regularly produce damaging hail, intense wind gusts, heavy rainfall, and other damage worldwide. Consequently, a broad understanding of the processes and dynamics that govern deep convective development and organization on a global scale is crucial for assessing the present hazard and future climate change scenarios. However, the simple use of broad-scale models and reanalysis datasets does not provide a framework to diagnose whether the generation of instability that drives convective processes is being reliably resolved. To address this limitation, we use the lapse rate tendency (LRT) equation to decompose the processes producing these environments and apply it to identify regions of effective sources, sinks, and transport of instability.

In the present study, we illustrate this new methodology by evaluating eight events producing intense precipitation in Australia between 2017 and 2018. Extending the approach, we apply the LRT equation to identify sources of instability to assess the crucial role of Lapse Rate (LR) in developing convective storm environments using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Preliminary results show that the positive values of the lapse rate tendency are strongly associated with the instability generation in storm development, though the contributing factors varying by location. Through these Australian precipitation events, the LRT positive tendencies provide a better indicator of convective activity than CAPE for tropical and middle-latitude storms. In this way, the LRT provides a practical diagnostic framework to assess instability generation and a way to evaluate model processed-based performance.