How Does Climate Change Affect Precipitation for Contrasting Tropical Cyclone Tracks and Evolutions? A Case Study of Three Atlantic Hurricanes

Landfalling tropical cyclones (TCs) are known to cause severe societal impacts. One of the largest contributors to these impacts is extreme rainfall and the associated flooding. Many studies have analyzed TC rainfall changes in a warming climate, and there is high confidence that TC precipitation will increase with warming. However, less focus has been placed on how future rainfall may change for TCs in different synoptic environments and at varying stages in their lifecycle. Does the rainfall from an extratropical transitioning storm respond differently to climate change relatively to a more purely tropical landfalling system? Here we begin to address this question by analyzing three Atlantic TCs that produced prolific rainfall over North and South Carolina that were quite diverse, synoptically - Hurricanes Floyd (1999), Matthew (2016), and Florence (2018). Hurricanes Matthew and Floyd were undergoing extratropical transition when they interacted with the Carolinas, while Florence was a more purely tropical system.

Here we simulate each of these storms using the Weather Research and Forecasting (WRF) model in a present climate, then in a future, high-emissions scenario climate using a pseudo-global warming (PGW) approach. With these simulations, we can then evaluate how each storm’s precipitation changes with climate change, and how that may differ as a function of synoptic environment and life cycle stage. To do this, we consider precipitation characteristics such as total accumulated precipitation, precipitation as a function of distance from TC center, and changes in the rain rate throughout the TC. To understand their synoptic differences, we evaluate these precipitation changes in the context of forcing mechanisms such as isentropic lift, frontogenesis, and large-scale flow patterns. Analysis of these three test cases contributes to our understanding of how TC impacts in diverse synoptic environments respond to climate change.