The models continue to depict a broken line of semi-discrete storms all the way into IL with this system. While the one limiting factor may be the depth and breadth of available moisture, the theta-E ridge is sufficient enough, given the shear associated with this system, to produce an appreciable severe risk. Given the H5 environment aloft, there is potential for cold core play more proximal to the low on the nose of the best lapse rates. That risk aside, I'll be watching the progression of the stratus deck through the late morning into the early afternoon. With the low near OAX by early afternoon, the models are indicating the show starts early closer to the triple point, then progresses to ignite ESE along the axis of a pre-frontal line of forcing. Past experience indicates that SRH is enhanced INVO this corridor, and with the possibility of a semi-discrete storm mode, I do think tornadic potential is enhanced the first 3-4 hours of the event.
The instability evolution will be interesting to watch. While moisture is perhaps sub-optimal for the most appreciable type of outbreak, it is climatologically sufficient, even if the NAM is slightly overdoing the northward extent of the highest TDs. A cursory glance at actual observations last night further south indicated that northward progression of really quality, deep moisture might have been slightly overdone by previous medium-range model solutions. Nevertheless, as previously mentioned, the actual evolution of the stratus deck will probably be the key component, so paying close attention to regional vis sat models will be paramount. Another cursory review of lower level RH values on this morning's 12z NAM and 4km NAM-WRF runs indicate the potential for some dry air making it into the more kinematicallty favorable region of the warm sector, which probably factor into the more appreciable MLCAPE being depicted across portions of S IA and N MO early tomorrow afternoon. With that having been said, past experience has seen this going both ways, i.e., we may not know how much or little, or where, the stratus deck with erode until nowcasting time tomorrow. This probably holds the key for how the tornadic potential evolves.
The triple point is always a synoptically favorable region, but I also think there is a conditional threat of one or two photogenic, perhaps stronger tornado reports further south across portions of IA, MO and perhaps even west central IL INVO the pre-frontal forcing mechanics in the area of the best thermodynamic energy, as progged 0-3 KM MLCAPE values on the last several forecast skew-T diagrams have been rather impressive. Again, this will also depend on how long storms maintain any semblance of being quasi-discrete, but embedded mesovortex rotations are not out of the question tomorrow either, even as the main line of broken convection moves into central and NC IL and points eastward. It initially looks like a lower topped convective show where storms will be moving at speeds >50 kts, so actual long-term chasing may prove difficult, especially in this geographic region.
