How do you reconcile these two statements, because it seems that there will not be a flood within 40-60 weeks on either end of the 730 days??

...events contain randomly select 40-60 weeks prior and post flood date, to ensure the flood event date is not always the middle index....

and

Somewhere in these 730 days per location/event ID there could be a flood.... If there is a flood for that event it can happen on any ONE of those 730 days.