Idealized Impacts of Mountainous Terrain on the Energetics of Hurricane Melissa (2025)

TL;DR

This paper investigates how mountainous terrain causes rapid weakening of Hurricane Melissa (2025) by analyzing observational data and an idealized model, highlighting the roles of friction, turbulent mixing, and other processes in storm decay.

Contribution

It combines observational analysis with a simplified model to quantify terrain-induced weakening mechanisms of hurricanes, emphasizing the importance of friction and turbulent mixing.

Findings

Approximately 50% reduction in peak tangential wind over land

Model reproduces 36% decline in kinetic energy due to terrain effects

Additional processes like asymmetric dynamics further contribute to weakening

Abstract

This study examines the decay of Hurricane Melissa (2025) as the storm crossed the mountainous terrain of Jamaica, focusing on changes in inner-core energetics. Using NOAA P-3 reconnaissance observations near the 700 hPa level, integrated kinetic energy within 100 km of the storm center was computed before and after land interaction to quantify vortex weakening. During the approximately four hour period in which the center remained over Jamaica, the storm experienced rapid degradation, including a 48 percent reduction in peak tangential wind, a 58 hPa rise in central pressure, and a 41 percent decrease in integrated kinetic energy. To investigate the mechanisms responsible for this decay, the observations were compared with results from an idealized axisymmetric tangential momentum diffusion model that isolates the effects of vertical turbulent mixing and enhanced surface drag. Despite its simplified physics, the model reproduces many leading order features of the observed weakening, including substantial reductions in tangential wind and a 36 percent decline in integrated kinetic energy. These results indicate that enhanced friction and turbulent mixing associated with extremely rough mountainous terrain can account for a large fraction of the rapid spin down observed during land interaction. Differences between the model and observations suggest that additional processes such as asymmetric dynamics, terrain induced flow distortion, and thermodynamic feedbacks further amplify the weakening of intense tropical cyclones over land.