The Bureau of Meteorology notes on its National Loop site that there have been some extremely weird things appearing on BoM radar imagery of late :
The BoM means these :
No-one from the BoM appears to have offered any explanation other than "technical difficulties."
But some who monitor or regularly check in on BoM radar, and have seen these "circular discs" are convinced the images are evidence of weather modification tests, or something much worse.
They certainly make for more entertaining explanations than boring old "technical difficulties."