I haven't seen enough history to know if that's normal or not, but I can tell you that the center of each of those blue "clouds" is a nexrad radar station. It's view is a wide cone from the ground upwards (technically a set of cones from each of the radar's tilt angles).
It's quite possible there is some lower altitude fog/precipitation/something that is only visible to the radar at it's lower tilt angles. But that's just speculation.
The NEXRAD weather radar system has multiple modes of operation (Volumetric Coverage Patterns) configurable for each antenna site. Each of these is optimized for different weather conditions. The light-blue returns represent humidity in the air (not quite rain or fog) and is usually tuned below the “noise floor”.
Radars uniformly set on high sensitivity. You're looking at the noise floor within [x] miles of the radar. The sudden smaller size of a couple was a manual dbm adjustment. They seem more common these days, I think because when you saw sharp cutoffs it was usually a threshold cutoff setting some human had to twiddle and humans don't bother anymore. This stuff drives some Boomers crazy and sets them to babbling about HAARP, especially the pacman shapes that represent a metallic obstruction near the center of the radar.
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[ 3.5 ms ] story [ 21.2 ms ] threadIt's quite possible there is some lower altitude fog/precipitation/something that is only visible to the radar at it's lower tilt angles. But that's just speculation.
I just wish we even had a radar where I live.
Current operating modes: https://www.roc.noaa.gov/branches/operations-branch/current-...