I'm thinking of going to Whitetail with my 10 y/o son (a fairly new skier) next Saturday, but there is rain forecast as late as Thursday. They should be able to blow snow on Friday night if not Thursday as well. Is that enough time for them to get the slopes back up to the typical "packed powder" status? 

Should be just fine. They have some great grooming and snowmaking out at Whitetail.