Investigating the Role of the Upper-Levels in Tropical Cyclogenesis

Despite decades of theoretical research and observational studies, a good understanding of Tropical Cyclone Genesis (TCG) remains elusive. One recent theory proposes TCG is contingent upon a necessary condition in the lower tropospheric levels whereby a closed circulation exists in a Lagrangian framework forming a protective region for genesis. This thesis work contends that while lower-tropospheric forcing is necessary, it may not be sufficient, and the upper levels can have an influence on TCG. Specifically, enhanced divergence aloft as well as outflow vents are key differentiators between many developing and non-developing systems. Composite fields, 3-dimensional multivariate analyses, and case studies are examined to identify the roles that the upper-level flow environment can play in TCG events. While likely not a forcing mechanism per se, the upper tropospheric environment can provide a modulating effect on tropical disturbances trying to develop, and should not be ignored when forecasting impending genesis.