I would not want to be in New Orleans this weekend:
From here: National Weather Service Hurricane Center
Here is a webcam situated on Bourbon Street.
The majority of Old New Orleans is built on land that has been reclaimed from the sea and protected by a system of dikes and levees. This land is now dry but it is still below sea level. A network of pumps move rainwater and leakage back out to the Ocean but it's capacity is fixed.
A storm the scale of Katrina could put parts of New Orleans under 30' of water for up to ten days or more.