I'm probably way off here but when I was looking at 500, I saw the ocean storm had a different look than GFS and was scooting out of the way - that and the vort diving down from the plains on the CMC was broader in the TN valley than the closed 500 low so I figured it would allow the surface low to reach our area vs being too far SE like the GFS. It honestly could have been a lucky guess on bad analysis lol