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

Michael Igbinoba

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.

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

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.
Paper Structure (11 sections, 26 equations, 3 figures, 1 table)

This paper contains 11 sections, 26 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Goals and Research Questions
  3. Methodology
  4. Observational methods
  5. Modeling Methods
  6. Results
  7. Observational Results
  8. Model Results
  9. Comparison
  10. Discussion
  11. Conclusion and future work

Figures (3)

  • Figure 1: Observed azimuthally averaged tangential wind, pressure, and IKE diagnostics from the first and second reconnaissance flights used in this study.
  • Figure 2: 3-km tangential wind, kinetic energy per unit mass, and geopotential height from the axisymmetric diffusion model at initialization and after 4 h of integration.
  • Figure 3: Time evolution of integrated kinetic energy (IKE) at 3 km within 100 km of the center from the axisymmetric diffusion model.