I reckon you found some sort of rotor Glen. Back in the lower North island of NZ where I fly (when I'm allowed home) the mountain wave off the Tararua Ranges often forms multiple rotor 'fronts' out to 30 miles. The secondary 'fronts' often can't been seen and have seen me in unintended aerobatic attitudes at times. On the positive side, I have rode the wave at times which can be fun. Its why the gliding altitude world record was set in 1968 in that area by the recently deceased Doug Yarrell https://www.stuff.co.nz/sport/other-sports/102076811/glider-record-still-soars-50-years-later