I commented on this sort of thing last September. New Orleans had a miss then when Ivan came to town. But it appears Ivan was a poor shot and minor caliber compared to Katrina--scheduled to hit tomorrow morning:
Hundreds of thousands of New Orleans residents fled inland on Sunday as Hurricane Katrina strengthened into one of the fiercest U.S. storms ever seen and barrelled towards the low-lying Gulf Coast city.
...
Katrina had a central pressure -- a measure of a storm's intensity -- of 902 millibars, which would make it one of the four strongest storms on record. The Labour Day hurricane of 1935 that hit the Florida Keys, killing some 600 people, was the strongest with a minimum central pressure of 892 millibars on landfall.
They are evacuating the city. It's quite possible this will be the last evacuation. The city is below sea level and it is only going to get worse as time goes on. As I said last year:
My belief is that long term the people and businesses of New Orleans should close up and move out. Barring some extraordinary technological breakthroughs in earth moving (I'm talking raising an entire city from deep down under the water soaked earth) and/or lowering the sea this battle cannot be won. It's better to surrender gracefully than to let the enemy annihilate you. Spend the billions on salvage and rebuilding in another location, but surrender the current New Orleans to it's muddy grave.
This could be the end of New Orleans. Interesting times we live in.
Update: I've been reading some of the articles about Katrina and New Orleans. They are incredibly sobering.