Parallel track is a recent thread and here is a quote from Bob concerning parallel, converging and diverging tracks...
Yes, I think the point is made that in good skiing, "parallel" is a coincidence--and perhaps a rare coincidence at that. As a goal, it is false! As a measure of expertise, "parallel" is nearly irrelevant. I suggest that beginners and low-intermediate skiers making skidded, braking turns are likely to be more parallel, more often, than experts!
BTS--you have described well a typical scenario in high-performance carved turns, like those in the Japanese video clip. When the outside ski is tipped to a higher angle than the inside ski, and suddenly receives more intense presssure, it will for sure bend into a tighter arc than the inside ski. That does happen often in, often somewhat after, and occasionally well before, the apex in tight slalom turns. When the skier knows that, and moves the inside ski in preparation, all is well. When he "forgets," it can be a disaster, with the outside ski carving into, and even underneath or over the top of, the inside ski. Bad things happen then!
So many things influence these various outcomes: edge angle, amount of pressure, fore-aft focus of pressure, left-right pressure distribution, and muscular steering activity of both legs--and/or of the upper body.
Snow conditions, too, often play a role. One of the most hideous injury scenarios in skiing results when a modern slalom ski's tip suddenly bogs down into soft snow, causing it to bend and arc tightly into the turn, which combined with suddenly slowing down, dramatically further increases its tip pressure, in a vicious cycle chain reaction to disaster! I have three friends, very high-level expert skiers all, who have suffered severe boot-top leg fractures from this mechanism.
Yes, "parallel" is an illusiory coincidence in expert skiing! As the tracks and movements we've discussed here clearly reveal, expert skiing involves diverging skis, converging skis, and--only occasionally!--parallel skis.
Consider that even in the tracks that might appear most obviously parallel, forming concentric equidistant circles, as might be the case when carving all the way around a 360 degree arc, the skis themselves will not
be parallel! As the inside ski track is tighter, the ski tips will obviously diverge. And the divergence will be greater, too, because the inside ski is typically advanced ahead of the outside ski ("tip lead"). As it is futher along the circle, it must obviously point the direction the outside ski will point later, when it gets to the same point. So it often requires diverging skis to carve even the most "parallel" tracks!