Good question! This is instrumental in this system's future. The shear was not very well modeled.

There has been strong diurnal convection in the lower Mississippi Valley the last 2 days and this is fluxing convective heat release into the atmosphere in the area and into the SE U.S. That raises heights because of the heat insert causing an expansion of the medium -- like filling a balloon. But there is no rubber boundary in the atmosphere so the expansion causes the wind to increase as it flows outward from areas of expansion to areas of less pressure. The result is an increase in the ridge intensity over the SE, which causes increases wind flow into the weakness off the SE Coast. The trough appears stronger than modeled, because the models ultimately have not been handling the consequence of latenet heat release of convection in the deep south over the Mississsippi Valley very well.

I believe this is the cause for the trough digging into 75W and ultimately the shear stress on the system.