I've also been experiencing this bug the last few months.
I have windy open in the corner on one monitor in radar mode all the time. After a little while, it will skip out of the white 'real data' mode and then shift across to only playing the red forecast mode. This is without any intervention or input. If i click back into the white bar it will then loop only the white bar for a while until it pops again and gets stuck in forecast mode.
Id settle for either disabling forecast mode as an option or fixing the bug.