I long range hunt in mountainous terrain for deer and bear and the only way you'll know what's truly going on is to hunt the same area for years and see what the normal prevailing conditions are. You also will need to know your rifle and how it's effected in different conditions. Experience and lots of practice shooting in wind will ultimately be the deciding factor on whether to take the shot or not. If you you don't feel secure in taking a shot when wind is present your in the wrong game as wind is almost always a factor here. It's impossible to know what the wind is doing at different ranges across a canyon. All you have to go by is what it's doing where your at and what it's doing where your bullets going to land. The wind in between is nothing but a well educated guess. I suggest practice, practice, practice shooting in wind and see how it effects you bullets flight.