Good god this is some extreme wording.Snippet from a discussion just posted by OUN, they expect supercells throughout the event.
EVERY storm will be equally capable of producing dangerous tornadoes and destructive hail. Many (most?) people will NOT see any storms at all! We are only expecting a small number of storms. We could have 2-3, we could have 10. The thing to remember is if you see a storm near you, assume it's a dangerous storm. We have not experienced a day like this in quite some time. We expect storms to become supercells quickly after they form, and they should remain supercells through the event. We do not expect them to form into a squall line or cluster. The potential for tornadoes will INCREASE after dark, so do not let your guard down. Wind shear - which is already plenty for tornadoes this afternoon - will only become more favorable after dark. This is important! Clouds will NOT prevent storms from forming today or lessen their severity. The cap (a layer of warm air above the surface) will NOT prevent storms from forming today.