Additional convection is now going up, behind the initial supercell, from around Langtry, TX south to the Serranias del Burro.
Unfortunately it is going to be difficult to clearly see any rotation on the initial supercell near Brackettville as it passes near/over the radar site. Radar imagery should get better again once the storm approaches the east end of the current warning polygon (provided that severe weather doesn't damage the radar, of course).