The overall look of the system on satellite vs recon reports is a bit troubling, I don't think the mid-level dry air did much other than make the heat engine sputter in the storm, the pattern above it is setting up potential for a fairly rapid intensification phase, especially as it moves into the extremely warm waters of the Northwest Caribbean.

The warmest Caribbean waters are roughly in a box with the western tip of Cuba in one corner and Jamaica in the other. Ernesto is forecast to stay south of that, but the waters there are still quite warm (warmer than where it is now)
In short it's a pretty good bet Ernesto becomes a hurricane tomorrow, and has an honest shot at becoming a Major in the western Caribbean Monday or Tuesday.

Note the latest recon fix is further north than the first forecast position from the 11AM EDT forecast.