Oh my, Katrina is now a category 5 hurricane. Hopefully she will both weaken a bit and not hit New Orleans.

New Orleans is like a bowl of chocolate pudding with the city pressing down on it’s skin. You can stand on the street in New Orleans and gaze up and over the levee to watch the huge ships above you..

John McPhee’s most excellent book Control of Nature has a section about all this.

Levees are an beautiful exemplar of public goods. Public goods come in various structures and levees are at one of the extremes. The quality of the levees is defined by the worse section of the leeve. The minimum over the set of all contributions defines the quality. In the early days, during a storm, men would get in a boat and head across the river to break the levees on the other side.

In the last century the Army Core of Engineers has spent vast sums of money keep the Mississippi river flowing past New Orleans. It really badly wants to switch to a different course far to the west.

Later, around noon east coast time

“Mayor Ray Nagin ordered an immediate evacuation Sunday for all of New Orleans … police and firefighters would fan out throughout the city telling residents to get out. … police would have the authority to commander any vehicle or building that could be used for evacuation or shelter … The hurricane’s landfall could still come in Mississippi and affect Alabama and Florida, but it looked likely to come ashore Monday morning on the southeastern Louisiana coast, said Ed Rappaport, deputy director of the National Hurricane Center in Miami. That put New Orleans squarely in the crosshairs.

‘If it came ashore with the intensity it has now and went to the New Orleans area, it would be the strongest we’ve had in recorded history there,” Rappaport said in a telephone interview Sunday morning. “We’re hoping of course there’ll be a slight tapering off at least of the winds, but we can’t plan on that. So whichever area gets hit, this is going to be a once in a lifetime event for them.’… “We’re in for some trouble here no matter what,” he said. (more)

The photo at right is a sheet of plywood driven thru a palm tree by Hurricane Andrew, the last category 5 storm to this the US. More pictures here and here are pictures from Camille another category 5 storm which hit near New Orleans in 1969.