typhoon_tip and HF pretty much hit the nail on the head regarding 95L out there and subtropical vs. tropical cyclones, so I'll only add a few tidbits.
You can get a lower-level warm core (like you see in a tropical system) when you have convection firing near the center of a cold-core system. More often than not, this convection is a response to the process of gathering heat and moisture from the ocean's surface going, which can lead to the development of this lower-level warm core. (Note that convection does not directly provide the heating for this, though!) If it goes on for long enough given other favorable conditions, you can get a subtropical cyclone out of it.
If the convection persists, the inner core gets going (maximum winds move inward toward the center of the storm rather than found well removed from it), and underlying conditions are still favorable, you can get an upward growth of this warm core into the upper levels. This is what brings about "tropical transition" and the development of a tropical cyclone.
(If any of this is too technical/scientific, please send me a message and I'll try to clarify.)
The identification of subtropical cyclones and tropical cyclones growing out of extratropical systems has really taken off in the past few years, largely in response to having someone at the NHC really keen on those hybrid-type of storms (Jack Beven) and at least partially in response to the cyclone phase space (http://moe.met.fsu.edu/cyclonephase/) that helps identify those storms with a fair degree of accuracy. You'll probably see some subtropical phase added to Vince in the final report and, if this develops, probably here too.
The satellite appearance of 95L continues to improve, with convection trying to wrap around the southeast side of the storm (and, more importantly, persist). QuikSCAT wind fields suggest a rather broad wind field, albeit one with maximum winds relatively close to the center of circulation. Not all of the 00z model guidance is in, but the available guidance (Canadian and UKMET) show that the system is completing tropical transition now and has had a shallow warm core for some time now. This agrees well with what the other models were showing in terms of forecast evolution earlier today. (Note that this discussion follows from the diagrams at http://moe.met.fsu.edu/cyclonephase/.) I imagine the NHC is waiting for a little bit more separation from the trough to the north of the storm before pulling the trigger on this one; it's likely only a matter of time before they do so. It'll probably start as a subtropical storm before becoming a tropical storm -- Delta -- shortly thereafter. We'll see what actually pans out over the next day or two.
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