Severe thunderstorms (STs) are an extreme form of storm clouds that produce large hail, damaging winds and/or tornadoes, and torrential rainfall. There is increasing concern about how these “deep convective” clouds are changing in occurrence and intensity. earth system models (ESMs) are used to understand these ST systems, yet two significant problems persist with the previous research: (1) coarse resolution ESM simulations only account for the large-scale environments, thus ignoring the smaller storm-scale physical processes and how they feedback to the storm’s dynamics; and, (2) there is a built-in assumption that the mechanisms controlling ST initiation will not be significantly different in the future.

This research addresses the two issues by answering major overarching science questions:

Q1. What are the significant interactions of storm dynamics with the specific environmental factors of land-surface, atmospheric particles, and extreme precipitation that affect ST occurrence and intensity? How do urbanization and wildfires affect ST characteristics over the central United States (CUS)?

Q2. What are the overall effects of the compounding extremes on ST characteristics over the CUS?

The objective of this research is to improve the foundational understanding of key physical processes that impact ST characteristics. First, the research will focus on of the impacts of urbanization and wildfires, as well as explore the feedback of extreme soil moisture resulting from extreme precipitation to the subsequent ST formation and intensity. Second, the research will provide a comprehensive performance assessment of ST characteristics in a new regionally refined ESM with advanced formulations of dynamics, urbanization, and wildfire. Third, this research will provide a robust understanding of how ST characteristics change in the CUS by considering the compounding extreme events of droughts, extreme precipitation/flash floods, and urbanization.

The grand deliverable of this research is advanced understanding of ST activities in the past and future by investigating previously unexplored links between STs and the evolving Earth system, which is affected by wildfires and urbanization. The research will fill a significant gap in understanding the important physical and dynamical interactions involving microphysics, atmospheric particles, the land surface, and precipitation that affect ST characteristics.