An excellent example of the affects of changing upper winds is how a 'mountain wave' condition effects the IAS of jet aircraft. I have seen changes in excess of 20 knots or more, plus and minus in these conditions. Although it is termed 'mountain wave', it can be encountered when not flying over mountainous terrain.
The worse I was ever in we went from the Mach warning going off to the stick shaker in a matter of what seemed just a few seconds, this was in a 727 over the Rocky Mountains one night. Needless to say we descended as soon as we could. By the way, there was no turbulence involved. Sometimes you can actually feel the wave before it affects the aircraft. It will sometimes feel as if the back of the aircraft will start rising, as if going down a ocean wave on a surfboard.
For some reason this seems to happen more at night, why I've not a clue. While encountering these wave conditions can be very irritating, I've never heard of an accident happening because of a mountain wave. I'm not saying there never has been, I just cannot recall any.
As for a legal document, all I can suggest is to Google 'Mountain Wave' and see what comes up. What ever comes, I don't think it could be called a 'Legal Document'.