At 04/12Z, ex-TD Gaston (Invest 09L) was located at 16.3N 45.6W moving west to west northwest at 13 knots. Good convective signature sheared slightly to the west with sustained winds again at 30 knots, so I'd anticipate ex- Gaston regaining Tropical Depression status today (Saturday).

An elongated upper level low is located ahead of the system near Puerto Rico, but the low is moving to the southwest. With some southerly shear ahead of the system, conditions would favor a slow intensification process, yet SHIPS intensifies the redeveloping cyclone to a hurricane by Tuesday and even to major hurricane status by Thursday - probably a bit too aggressive. Some of the longer range projections take the cyclone just to the south of Puerto Rico and Hispaniola while others suggest a track just to the north. Given the movement of the ULL and the ridge expected to rebuild to the north its going to be a tight call - the Leewards, Puerto Rico and the Dominican Republic are likely to end up in the eventual cone of this redeveloping system.
ED