the point is, the trough can start breaking down the high currently steering the system well before it gets close to Irma.
Oh, agreed, but how much and from how far away?
What I think we are seeing tonight is a “wobble”, south, and then back north, and the real effect of the trough (a strong turn that is maintained) is still some hours away. But, that’s just my guess. I believe there are some upper level westerly’s in the equation, too.
If Irma determinedly begins to curve north now, oh, golly...