How long do you think it would take to figure it out? The schools are suddenly empty, there's no one in the commissary anymore, the American neighbors all moved out, and the economy around military bases suddenly takes a nosedive. Trust me, people will figure it out in about five minutes.
Yeah, I remember those noncombatant evacuation drills too. It seems to me they were all based on two weeks advance notice of a Soviet invasion into Western Europe. They certainly tried their best to make them realistic, but...
Onward and upward,
airforce