Weather radar doesn’t look upward very well, but rather out to the sides. They place weather radars and National Weather Service stations outside and mostly downstream of large cities, so they’re able to watch events as they unfold over the major population center. NWS: Norman watches Oklahoma City. The dark area in that image is just the artifact of not being able to see what’s overhead in Norman.
Is the radar facility located well to the east-southeast of Norman? The apparently dry area is nearly circular, which would jibe with some sort of radar artifact, but with evident rotation around the periphery on all sides. It’s not moving much. I wouldn’t be at all surprised to see that loop pop up on some conspiracy oriented site, since it creates something of an illusion of directing the cell away from Tinker AFB, which is just beyond the edge of the cell into the black apparently dry area. It really is unusual looking, to me and at least one other FReeper. I’m no meteorologist but I’m not a complete novice, either. Can’t honestly say I’ve ever seen anything quite like that before.