A storm surge is water that is pushed onto shore by a hurricane. It is rarely a "wall of water" as often claimed, but rather a rise of water that can be as rapid as several feet in just a few minutes.

1. Katrina makes landfall in Louisiana at 6:10 a.m., but the flooding of residential areas in greater New Orleans actually begins an hour and a half earlier. Between 4:30 and 5 a.m., levees ...