Last night I was watching the Ryan Hall livestream and he explained that since this system has so much shear, It didn't take much to kick off strong, severe storms. THere were a lot of tornado warned cells last night on the pre-front line of storms, and then more in the actual frontal passage. I think there was even one or two areas which had different tornado warned cells pass over about an hour apart.
I am definitely not a knowledgeable as many of you on this, but just wanted to pass that along.