Not often you see two tropical systems close enough together for a Fujiwhara effect so far north and east in the Atlantic. I sense that the area of current activity will become an increasingly active region in the decades to come.
As to your question, well I read recently on the Wunderground site that for some reason, the models aren't fed isotherm depth data and so work on the assumption that the surface temps extend way down below the surface. This doesn't impact ex-tropical cyclones much, if at all, but for tropical ones it often leads to errors such as you describe.
This also comes into play where the ocean is shallow as the model doesn't know how deep it is; that's what led to them keeping Florence too strong as it approached the U.S. (they're much more on track now that Florence is right by the coast, as the Gulf Stream is effectively giving it an inexhaustible heat supply to work with despite the shallow water).
I'm not sure this explains the whole situation though, because Ophelia of last year, for example, managed to exceed model projections in hitting major hurricane status while SE of the Azores. Perhaps there comes a time when the increased Coriolis effect becomes the dominant factor?
That being a reason why I fear for what the Central Atlantic might produce in the decades to come; sufficient oceanic warmth reaches areas with a greater Coriolis 'boost' to cyclonic rotation than ever before in the basin.
Originally Posted by: Stormchaser