Updraft-Scale Dynamics of Tropical Cyclone Intensification

Toward improving tropical cyclone (TC) rapid intensification (RI) forecasts—still among the greatest challenges in our field—we investigate the nonlinear, updraft-scale mechanisms associated with RI. While small-scale processes associated with RI are extremely difficult to observe, we hypothesize that a better theoretical understanding of updraft-scale dynamics within the TC inner core will lay the foundation to improve: data acquisition and model development strategies, the forecast process, and ultimately the communication of TC hazard risk in support of the NOAA mission. In this presentation, we aim to better understand the processes associated with the rapid growth and concentration of vorticity that occur during RI.

The focus of this study is on Hurricane Fiona (2022), which intensified quickly as it approached Puerto Rico on September 18, 2022. Fortuitously, a plethora of high-resolution data, including ground-based NEXRAD and NOAA P-3 tail-Doppler radar data, was available during the short-term intensification. We will present an analysis of the observational data, short-term forecasts from operational models, and highly idealized simulations to describe the mesoscale and updraft-scale evolution of deep convection during Fiona’s intensification. More general implications for RI and TC intensity evolution will also be discussed.