Interesting discussion simmering here. And what a very interesting storm we have!

Classic case of (attempted) tropical cyclogenesis on the trailing end of a decaying frontal boundry. I've watched this storm sprout up, like many of us, from it's inception, as its parent front moved off the atlantic coastline a few days ago.

And while it certainly has been looking rather impressive the past day or so, it's also true that "appearances can be deceiving".

First, here's a few bits & snips from *Yesterdays* posts on this interesting system from Raymond, Rodney, Hugh and others:

Which brings me to the crux of the matter. The development of the warm core. It's this innermost convection that will 'make or break the case' for tropical or sub-tropical transition. Because it's precisely these thunderstorms with will, under the proper conditions, lead to the development (formation) of the tropical warm core.

And this ties in well with the question ... "Could somebody please point me to a good (basic) definition of what a system needs to do to be considered extratropical, subtropical or tropical?"

Above all, to be classed as a *true* tropical system, you need for the storm to have a 'warm core', relative to it's surroundings, through a deep layer of the atmosphere.

And so far, this just hasen't happened. But it now appears to be (finally) taking place as the LLC center is just beginning to move over the warm gulf stream waters.

These warmer waters will result in stronger thunderstorms, and more of them which, when acting in an organized fashion as they are now, and over time, will will release such a tremendous amount of latent heat of condensation, that it will actually *warm the entire atmosphere* over hundreds of square miles, and a bona-fide tropical cyclone is formed.

Although the wrapping we've seen previously certainly *looks* impressive, especially on the visible loops, the IR and Water Vapor loops tell a different story:

Until quite recently, this inner convection hasn't been partucullary impressive and certainly not very deep, as shown by the relatively warm cloud tops (compared with 93L), and the water vapor imagery suggests that not very much vertical transport of moisture (deep convection, with it's attendant latent heat) has occured yet, until quite recently.

Also, until recently, the doppler returns out of Wilmington, although suggesting the formation of a ring-like feature, have not been especially strong, either. And most of the deeper storms seem confined to the NW semi-circle.

But now, that all seems to changing, and quite rapidly, too. The warmer waters of the Gulf Stream now appear to be imparting better 'fuel' (has to do with higher vapor pressure) for the increasingly organizing thunderstorms, and as more and deeper convection continues to develop, the result will surely be the formation of the infamous warm core and an 'upgrade' to at least subtropical status, if not 'true' tropical transition sometime before landfall.

Keep one eye on the doppler radar for stronger and 'thicker' echo returns and the other on IR cloud top temps for dramatic cloud top cooling (especially after sunset, with the onset of the diurnal convective max cycle) and I think we will be witnessing tropical cyclogenesis right before our very eyes! Will we be having a landfalling 'Laura' ? Down to the Wire!