Late season tropical cyclogenesis in the western Caribbean Sea and Gulf of Mexico

The focus of this presentation will be on late season (October and November) North Atlantic tropical cyclogenesis events in the western Caribbean Sea and Gulf of Mexico. Examples of recent late season tropical cyclones (TCs) that formed in these regions during the 2004-2009 TC seasons include Wilma (2005), Lorenzo (2007), Paloma (2008), and Ida (2009). This presentation will emphasize the rich spectrum of pre-genesis environments and physical genesis mechanisms associated with the formation of late season TCs in the aforementioned regions.

A brief climatology of late-season TC events will be presented for the purpose of introducing selected pre-genesis environments and physical genesis mechanisms. These physical mechanisms include storm spin-up in regions of ambient low-level vorticity associated with: 1) the equatorward ends of decaying weak cold fronts, 2) ITCZ breakdowns, 3) trade-wind surges and gap flows, and 4) the convergence zone between monsoon westerlies and trade-wind easterlies. The results from one or two illustrative case studies drawn from the above-mentioned sample of TCs will be presented to better illustrate likely operative physical genesis mechanisms.