To summarize Carolan's rationale, he points out that there are three types of cyclones in the atmosphere: warm-core, cold-core and hybrid. Only a warm-core cyclone can be classified as tropical (hence why they immediately stopped calling it Hurricane Sandy when cold air started getting into the core of the cyclone, and why we're stuck with that silly Superstorm label-- I was disappointed Frankenstorm didn't stick to be honest), and Carolan is arguing that Andrea was a hybrid event.