So, ALL the radar sites have their gain turned up high in those cities? I'm going to check the link for all the regions, and see if there's more of this elsewhere.
Best description yet:
Clutter
Ground Clutter is the most common false echo and is usually seen in every radar image. When atmospheric conditions are such where there are low-level inversions (air temperature increasing with height instead of the typical decreasing with height) ground clutter can be very pronounced.
Ground clutter is the easiest false echo to recognize since it does not move in any organized fashion, it has no kind of structure to it that is similar to real precipitation, and it is usually close to the radar. The ground clutter in clear air mode is often more prevalent than precipitation mode. This is because the radar is in its most sensitive operation thereby “seeing” smaller objects such as dirt, dust and bugs.
It looks like a failure in some computer enhancement program designed to reduce ground clutter in the nationwide composite map. I’m saying this because all the radars with the circular patterns are in the midwest.
That would indicate that some office isn’t paying attention — probably paying attention to the flooding and not the radar.