That level of probability was not reached until after 4:00 PM Sunday.
Wrong, the computer models were converging on a SE LA hit as early as Friday morning, the official NHC track was shifted westward to Pascagoula (within 90 miles of NOLA) for the 4pm announcement, with the note that further moves westward were very possible, which indeed happened with the updates Friday night.
4pm Sunday did not leave much time, maybe 12 14 hours? I liked dirt-boy idea about 2,000 school buses. I remember looking a probability maps after Kattrina hit Fla and recall Fla pan handle the predicted hit. I don't think the blame game is fair, NHC does it's best and it does an excellent job, but until the storm is in strong steering currents there predictions can be way off. I do think N.O. could have had a better plan since N.O. is so at risk, hopefully cities like Galveston and Mobil will see what awaits them if they too fail to plan for a worst case evacuation.