Arriving in Marshall, TX at 4pm, a rapidly developing storm was observed to the immediate west. The storm quickly became a supercell as it moved to the east around 30mph. We pushed closer along Hwy80 west of Marshall and stopped with a good view to the west. By 4:40pm, we had a clear view of the storm as it moved over Hallsville. The storm structure was quite impressive, complete with a persistent wall cloud and pretty vault. The storm continued to organize and large scale rotation was evident. Unfortunately, a left split from a storm to the south interacted with the supercell which resulted in the slow demise of the overall organization. The storm certainly made for a pleasant chase day across east Texas.