How much time do you need? While a specific warning for NO may not have been as soon as the knowledge of Katrina was available, that knowledge of a hurricane in the gulf was far more than 40 hours. No one says leave, but you can make preparations so when the warning comes, you don't waste time doing what you could have already done.
"How much time I need" is irrelevant to the poster's blatantly ignorant claim that the path of a Gulf storm like Katrina can be predicted five fucking days in advance. Anyone who's ever lived anywhere near the Gulf knows what an unmitigated crock that is.
Moreover the presence of "a hurricane in the Gulf" doesn't mean it's coming "HERE". The current storm in Texas was "a hurricane in the Gulf" too. If everybody evacuated every time there was "a hurricane in the Gulf" they'd be driving back and forth continuously for three months.
And again -- it wasn't Katrina that devastated New Orleans. That came and went without much incident. It was the faulty levee system that gave way and brought the flooding after the storm was long gone. I actually sat up all night with a battery-powered radio listening to it begin, via live reports from where I had evacuated 150 miles inland. Those who didn't evacuate and were not in a flood area, including my neighbors on my street, got through without incident. A flood wall breach can't be predicted, especially not five fucking days out.
Again, I could sit here and "predict", on the basis of no info at all, that the Chicago Cubs will lose their game on May 5 2023 by a score of 5-3. If that day comes and that actually happens, it doesn't mean I'm freaking Karnak. It means I was lucky to hit on a coincidence. There's no basis to predict that. What we have here is a poster as usual pulling it out of his ass to try to score "points" on a message board.