The evacuees have clearly waited until the very last moment to abandon the condo, which would be foolhardy at best--not to mention the inference that the then early-FEMA authorities were recklessly lax as to when they should issue their evacuation order in the first place. The notion that said evacuees could simply drive away in their cars (or escape in a small powerboat!) to avoid such obvious danger is, of course, quite ridiculous though ostensibly the screen-writer's device to increase dramatic effect.