Big and Tall: New Insights into Hurricane Structure and Intensity Change
Tropical cyclones come in many shapes and sizes. We have known for several decades that there is no single relationship between the horizontal size of a tropical cyclone and its intensity, with many different combinations of minimum surface pressure, maximum wind intensity, radius of maximum winds, and outer core wind strength that have been observed. Observations also show variability in how the winds, thermodynamics, and precipitation change with height. A key scientific question is whether certain radial or vertical structures are preferential for ‘rapid’ intensification, which can reduce the time needed for coastal areas to prepare for impacts. In this talk, I will present recent research that investigates the relationships between radial and vertical structure of tropical cyclones and their intensity change using observations and numerical modeling. This research indicates that the initial structure of an incipient cyclone plays a significant role in its subsequent evolution, with small storms tending to remain small and large storms tending to grow larger over time. The vertical extent of the wind field is also important, with taller storms more likely to undergo cyclogenesis and rapid intensification. The ability to achieve a structure that leads to subsequent intensification depends strongly on environmental factors, including vertical wind shear and ambient moisture. Implications for predictability and directions for future observational capabilities will be discussed.
