Hmmm, off the cuff I would say in Noah's time the terminus point was when it began to rain. Since it had never rained before, I think that would have been a good point to stop partying. Do you think that "sudden destruction" isn't that "sudden"? That once it started to rain, attention got focused on the events, but, that destruction/death in a sense didn't happen until the water got high enough to drown in? Hmmmm, think I see where you are going. The events leading up to the "destruction" begin suddenly. Maybe?

Chris