Maybe it was inadvertently running in some odd mode that displayed ground clutter or a pocket of very moisture rich air as rain. I can't see any sort of operational mode imbedded into the image. Maybe hackers testing to see if it can be done on a targeted basis.
Plus there were no chaff streaks
Chaff can be deployed in streaks or in blobs. Both are common. It can also be released by multiple aircraft/rockets at multiple altitudes, or a thermal could lift it above its deployment altitude, especially since this was the afternoon.
Of course, it would have been easier to claim it was a chemtrail or HAARP related, but I decided to leave that to the experts. ;-)