A hurricane is threatening to hit and even though the city sits 8 feet below sea level, you choose not to evacuate or even prepare because you've seen many hurricanes threaten to hit the city and it never makes landfall, so why prepare for this one? Days later, your great city is almost completely flooded from Hurricane Katrina and over 1,800 lives were claimed including some of your neighbors because, like you, they decided not to leave the city. Now you are left without electricity, water, and dwindling supplies. To make matters worse, supply trucks are cut off, the police and emergency services can't meet the needs of the people and there are looters breaking into homes for supplies. 

Yes, the above scenario is a worst-case scenario, but aspects of this are very common following hurricanes. These tropical storms are extreme and have the capacity to cripple our entire way of life.