I'm sorry... I just don't understand what you are asking.... I don't think Jesus was forecasting anything... I think He was telling the Pharisees that they needed to change their lives as the Ninevites had done when Jonah was sent to them. Like I said... they didn't have clocks back then... generally so they weren't real specific about time.....seekeroftruth,
re: "What was common?"
To say that it was common to forecast or say that a daytime or a night time would be involved with an event when no part of the daytime or no part of the night time could occur.