I think it's a good and somewhat bad idea, it's good for all the reasons all of you have said, plus you wouldn't have to worry about extreme traffic or panic on the raods as much like what occured with Katrina when they had to turn all lanes in one direction out of New Orleans, but I get a bad feeling that it may cause more people to procrastinate about evacuating and foolishly deciding to ride it out. It's almost the same with tornados, you can get over 30+ minutes of warning time, but people do wait until the last minute to take shelter to see if it's a false alarm or if it will just pass right around them. I did the samething when we got hit by a tornado two years ago. Overall it's a good idea, I just hope noone ignores the extended heeded warnings.