Supercells that form in front of the initial line (front) will have the best chance at showing rotation and producing tornadoes. These are already getting fired up in West Mississippi. They will last until the front moves through. The front will be more of a line of very strong storms with high winds. It will move through west MS 2-5 and east MS 5-8AM.
I don't see a flash flood watch issued, but theres always a chance when you get "training" from some of these stronger storms. Right now it looks like they are moving along pretty fast.