aha here’s a full explanation of the thought process:
no other weather report matches these patterns
they’re suspiciously round and not blobby like real clouds
they’re each suspiciously localised around the radars in the network
there are lots of types of radar artefacts, including close-to-radar ground-clutter (this is what I assumed it was) but it’s too consistent and large of a signal for that
so it must be something uniform, in the air instead of on the ground, that isn’t rain
bugs are about the size of a big rain drop! enough to be picked up as a strong signal by the radar and enough to prevent the radar from seeing long distances
It’s also been flying-ant-day recently across Europe
what a roller coaster, and the ominous unexplained insect edit is a cherryon top
aha here’s a full explanation of the thought process: