Being at close range, and 15ft up. Its probably good chance your pass through came out low, which would explain the white hair. Bright red blood usually indicates a good vital hit in the lungs. If you got both lungs he didn't go far. Did you hear any noises from the deer when he ran. I've heard deer gasping for air when I've gotten both lungs. The rain is definitly a problem for you, but don't give up hope. You'll have to go by his tracks, punch marks left in the ground, and hope to find what blood you can if any. If you can't find him, you may want to look into deer recovery dogs. They are capable of tracking by scent even after it rains. Good Luck!