The underlying concept of dipolar vorticity source and attendant vorticity streamer, excited and modulated, in part, by the regional flow affords a nice model-theoretic picture of advective and non-advective fluxes of isobaric vorticity substance documented in the classic works of Haynes and McIntyre 1987 and Schär 1993. Also highlighted is the nonlinear downstream development of closed vortices, which requires an intermediate range of regional flow speed to develop within the target region (SW Caribbean). In this circumstance the phenomenon resembles a kind of one-sided von Karman vortex rollup, owing the spatial asymmetry and temporal pulsation of regional flow and source mechanisms. Weaker flows do not result in separation from the coast, while stronger flows do not allow sufficient room for downstream development. Most flows vary in strength and direction with height, affording additional degrees of freedom.
The dataset used in our study is a 0.25-degree version of the operational GFS model in 2015-2017, and the results are evaluated in the broader perspective of ERA-Interim re-analyses 1979-2017. Examples of validated development are illustrated with geostationary imagery.