Contrary to what many assume wrt 99L having an opportunity to intensify south of the Greater Antilles in the Caribbean, this actually wouldn't transpire unless 99L was a very robust tropical cyclone, therefore, the only opportunity it has for intensification is if it passes well north of the Greater Antilles, even a close swipe by Hispaniola would severely disrupt any TC circulation that's not encapsulated by a complete eyewall... As the easterly trade winds are squeezed in between Hispaniola, Puerto Rico, and South America trade wind divergence is observed in the central Caribbean, which often completely will rip apart the lower level circulation of a weak tropical cyclone or at least delay genesis of a tropical wave until it reaches Jamaica's longitude. Later in the season towards October or so however, as a trough develops in the means over eastern North America, this typically cuts the trades to some extent and lessens the impact of this trade wind divergence (which likely helped Matthew last season)... There are rare exceptions (Charley (2004), Dennis (2005), Gustav (2008), etc.) where TCG and intensification of a weak-very weak TC can occur in this area of the basin, but 99L will almost certainly not be fortunate enough to join these rare exceptions...
This nice graphic overlaid with Earl from last year shows the relative dip in genesis between the longitudes of Puerto Rico and Jamaica in the Caribbean.
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