After studying the aforementioned sat loops I can say with some assurance that Dean is not doing anything unusual, nor is it separating or becoming two storms. The fluctuations you see in the Dvorak loop are entirely reasonable...hurricanes pulse in intensity and the CDO will reflect this, and is reflecting this. The GHCC IR loop is showing mesovortices rotating around the center...again, entirely normal and seen in strong hurricanes. Dean is extremely impressive on IR this evening, and is doing nothing unusual or rare....it is behaving just as a Category 4 storm should.

I don't see any eyewall contraction yet, and there has been no indication from Quikscat or recon of an outer eyewall forming, so I would say we are a bit away from an ERC...it certainly does not appear to be imminent.