And thinking through the various most likely situations, what are the facts and decision-points you have thought-through?

In as disaster / emergency your thought processes and decision-making abilities may well be compromised by the stresses of the event, so working out decision points in advance may be a lifesaver - especially if you want to respond early ahead of the crowd you may be competing against for survival.

Edit: It seems to me that if the best we can say is some variation on "I will decide at the time" or "I will go if there is an evacuation order," then we may be admiting we have not prepared to decide.