flooding, swamping entire neighborhood in oklahoma. declaring a state of emergency in a dozen areas. well another day, another round of severe weather across central u.s. it seems. meteorologist, derek van dam joins us from international weather center with more on that. we have been looking at those extraordinary size hailstones. what sort of weather system produces senate. you need a strong, super cell thunderstorm, andrew. we have had the setup for just that to play out over the central plain states. i want to show you some more ominous-looking clouds that were captured on film here in oklahoma city. this is called a shelf cloud. often seen along the leading edge of an approaching line of severe thunderstorms. that produce the large hail, andrew was talking about. show you pictures in a minute. accompanied by gusty wind. intense rainfall. passes overhead. time-lapse by the way. this actually forms when you get the cooler downdraft air. spread out in all directions on