I've found that even in a predictable wind, hunting lower in the valley especially where a couple of them converge can be very trickey. I hunt in a setup similar to this with 4 converging valleys. Problem is it has taken me years to learn exactly what the wind does. Seems like regardless of wind direction the wind in the valleys always follows my main valley which runs north/south. The more I move up from the bottom of the valley (which I almost never hunt) the more predictable the wind becomes. But even then too many factors come into play, open areas, groups of pine trees, thermals, etc. The best advice I could give would be to go there now while the leaves are down. Bring with you an arial photo of the site and walk around your area and note the different wind directions. Where I am, I can set up on the side of a ridge and have the wind moving from east to west (opposite of normal winds higher up the ridge) but if I move 40 yards in another direction it's completely changed. Like I said it has taken me a few years to get even decent with the wind down there and I still learn more each season. If you have flat areas at the tops of the ridges (unfortunatly I have backyards and houses) I would probably start there. the wind will be more consistant and you can overlook the valleys to get a good idea of where the deer move. Last season I had really good luck calling in a few bucks who were moving along the bottom of the valley while I was farther up particularly because they couldn't see the area that I was set up in very well until they actually walked up there. I think this played a key in preventing them from hanging up just out of range.