But you can't evacuate 4.5 million people. Can't be done.
Well, you won't get everyone out, as some will want to stay and a free society cannot force them.
However, we can get everyone out that wants to go. In theory, using all the resources available, it would take 33 hours to empty the threatened coastline. In practice, it's more like 72-80 hours, and we have that kind of time.
BS
It can be done.
We evacuated close to that many in the Florida fires of 1998.