Let me provide some prospective on the Ligety montage Tog posted.
The nature of the course set in this photo is dictating that the turns apex for the first gate is actually above the gate. That's fairly clear to see by observing that in image 2 his skis are already beginning to turn out of the falline, and he's already beginning his flexion into a retraction transition. Before that, in image 1, his hips are above his outside foot.
You must look at the relationship between the pelvis and the outside foot to have an accurate understanding of the hips to feet relationship, because the outside foot is where the skier is laterally balanced. In images 2-6 he is executing his retraction transition. Retractions require an intense flexing of the knees, which puts the hips well behind the feet. That pelvic position is clear to see through these transition images 2-6.
In image 7 he's rolling on edge, engaging the new turn, and beginning to lengthen his outside leg by extending his outside knee. Though this camera angle does not allow you to see it, by images 8-9 his outside leg is long and his hips have recovered to a position over his outside foot. As I said, it's hard to see here, but if you observe the amount of tip lead he has in images 8-9 you can get a better idea of the relationship of his pelvis and more rearward located outside foot.
Here are a couple more montages that provide a better view of the relationship of the pelvis to the outside foot at the turns apex.
The above montage is of Ted in a GS turn. Notice here he has abandoned the retraction transition and has employed a cross over variety transition. This is common in GS, where the need for a fast transition is not as great as it is in slalom. Cross over provides a better connection with the snow through the transition (less float), which provides better feel of edge engagement and therefor a cleaner initiation.
Now look at what Ted does with his hips. Notice between image 4 and 5 how he extends his new outside (uphill) knee, and thereby brings his pelvis up over his new outside foot for the initiation of the new turn. At image 6 his outside leg has already reached full functional extension, and at image 7 at the apex of the turn, at maximum edge angle, he has a long and strong outside leg, with his pelvis over outside foot.
Here's Ted again. Observe the transition between the blue and red gate. We'll call the image where Ted is right next to the blue gate image 1. Between image 1 and 2 is where the transition starts. Look how much Ted extends his inside leg between images 1-4. In doing that he has moved his pelvis up over his new outside (uphill) foot significantly, all before he has even reached edge angle neutral. By image 6, still well above the turns apex, he has already reached full functional outside leg extension, with his pelvis in front of his business foot (outside foot). Remember, the forward lean in a ski boot means a long strong outside leg also means a pelvis above or in front of the foot.
Will we always see the pelvis directly over the foot at the turns apex? No. Skiing is a dynamic sport, and different situations may require creativity in technical applications. Great skiing is characterized by the ability to adapt and adjust to need, and also the ability to vary what you do, just for the fun of it. Building a broad skill base involves developing the ability to venture comfortably into various ways of executing a turn. As a general rule though, in an arc to arc turn, achieving a long and strong outside leg with pelvis over feet before reaching the turns apex represents the strongest and best balanced stance for dealing with the forces that impact the body at that highest force level period of the turn. For skiers who suffer from perpetual hips and balance aft at all phases of a turn syndrome, which constitutes a good portion of the recreational skier population, aspiring to that long and strong apex stance can be an important enhancement to their skiing.
And to those who think the cross over transition is old school, that retraction is the new "correct", you only need to look at the montages I've posted above, and how much extension of the new outside leg is happening before edge angle neutral, to realize it's just not true. Retraction is gaining a faddish following of late, but it's not the only transition of value in modern technique, and certainly not the only transition the best skiers in the world are using. For the skier struggling to get out of the back seat, and to get their outside leg long and strong, going back to the cross over transition is a very effective way to break out of their "sitting on the toilet" rut, and learn this more efficient turning approach.