When everyone leaves the stadium at half time because their team is losing so badly. Especially effective term if the losing team makes a huge come-back and wins. Can also be used to refer to leaving a party or concert early just because it doesn't meet your initial expectations then hearing the next morning that it turned out great.
The newspaper reported a substantial premature evacuation in the third quarter, which despite the Bulls' turnaround for a stunning last-minute win, was hard on the team's morale.
When you evacuate well before a scheduled fire drill.
When the afternoon fire drill alarm goes off and all of the employees are already across the street at a Christmas party ... that's premature evacuation.
When people exit a building due to a drill or practice, however no actually emergency is occuring.
For the fire drill the students and staff did a premature evacuation of the school.