Originally Posted by
cardinal98
Initially I thought it might have been fuel dump for an emergency landing, but upon determining the flight was likely NRT->SFO (and not something that had just taken off) thought unlikely the plane would be overweight. Further, I believe dump is from the wings, not the tail.
FWIW, a fuel dump on the 47 will emerge very near the wingtips. A 777 about a third of the way inbound from the tips.