Interestingly this week and next is the group study on Noah in the "Imitate their Faith" book. It does not mention, as far as I can see, the fact there was no rain prior to the flood. Are they maybe moving away from this teaching like they did with the 7,000 year creative day?
I once asked a brother if there was no rain prior to the flood where did the rivers come from? He replied "Jehovah created them"!