Now saying this... "Multiple rounds of severe thunderstorms -- some capable of long-tracked tornadoes with EF3+ damage potential -- will be possible this afternoon into tonight over parts of the lower Mississippi Valley region and Mid-South."
Two things that really stick out to me is the lapse rates (pretty high for the mid South) and very high SRH. You're going to see some strong updrafts over there today with quick storm motions, just a perfect combo for long track tornadoes.