Hi bobkat, all that I can tell you is that storing wood on concrete is not a good idea. I don't know if it's the coolness of the concrete, or moisture exuding through the concrete, or a combination of both. What I've done in past years is simply to flip the boards over and let them warp back down the opposite direction. It'll take some of the bowing out and make them a little more straight. For future reference make some kind of raised area (shelving) for storing lumber, after all when you go to the local home center you don't see boards sitting on the ground. Good luck!