Sally Stade shows the overhead squat with the weight in front of the the frontal plane (top), slightly behind the frontal plane (middle) and directly over the frontal plane (bottom). In the top photo the overhead squat is potentially disastrous. In the middle photo it is safer, but not ideal. In the bottom photo, with the weight directly overhead, Sally's squat is rock solid.
21 Overhead Squats (Gents use 95# and Ladies use 65#)