For the next 48 hours, it looks like Isaac's major challenge will be that posed by interaction with the SW of Hispaniola and then Cuba. The NHC forecast and discussion suggests that little strengthening is expected - maybe a 10 kt boost, but mostly around 45 kts - until it emerges into the FL straights, if it lasts that long. I am not convinced that today is the critical period for Isaac. It may be more like the 48-72 hour period.

The NHC discussion at 0500 EDT indicates that Isaac is well skewed to the south with increasing altitude from the surface. This has no doubt distorted the view as seen by satellite images, which have at times given the appearance of a COC well south of the NHC reported positions. The MTCSWA , however,, shows a very well depicted cyclonic flow around the NHC's positioning. If you further look at the evolution of that analysis over the past 24 hours, it indicates clearly increasing organization at the surface level.

I suspect the big question is vertical organization over the next 48-72 hours as Isaac interacts first with Hispaniola and then Cuba. Will it pull itself into better vertical alignment, or will it remain tilted toward the south with increasing altitude?