I flew just east of that thing today on the SE arrival to IAH, coming in from Bogota... it was nasty looking, lotsa red and purple on the radar. I think it even shut down Hobby for a bit, heard some Southwest jets doing holding patterns over by Sabine and Beaumont. Glad we missed it!
From yesterday's squall line action in DFW - sorry for the poor quality and bad color correction, just a quick job. Got this after the squall line came over and the clouds parted. The cell you can see to the right blew straight up and built; I watched the lightning for over an hour from my office window.