Evaluation of Severe Local Storm Environments in Australia Using the Lapse Rate Tendency Equation

Severe storms regularly produce damaging hail, intense wind gusts, heavy rainfall, and tornados 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.

The present study illustrates this new methodology by evaluating three severe local storm events in three regions of Australia between 2001 and 2021, where we apply the LRT equation to identify conditions to favor destabilization by assessing 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 LRT are strongly associated with the resulting instability in subsequent storm development associated with both hail production and intense precipitation. Moreover, the nature of each event is influenced by different terms of the LRT equation, such as differential diabatic heating and horizontal and vertical LRT advection, which is evidence of their critical role in triggering storm development in Australia. This illustrates that the LRT provides a practical diagnostic framework to assess instability generation and other crucial mechanisms behind severe storms.