1971 VW bug generator light turned on and indicator lights flashing

This morning my bug was covered in snow, probably 30 degrees outside.
When I went up a hill and turned by wipers on at the same time, the wiper
blades stopped and my generator light turned on, together with the indicator
lights flashing. I didn't lose power in the car and I drove another mile to get to
work. Any ideas on what I need to check first?? The radio was also on but did
not die when this happened. The lights did not die either as they were also on.