YOu said he was broadside and your shot was about 35 yards. This would give you a relatively flat angle. The white hair indicates a low hit. Giving the information you wrote, I think you hit him low in the guts.

I would give him until mid-late morning before you went back out there. Since it rained and you have no blood trail, try to get as many people to cover the area. If you didn't spook him, he will probably be within a few hundred yards of where you hit him.

Good luck and post back.