When a mass outbreak of monsters occurs, the first to be noticed are always the fastest ones. If all the monsters were born in the same place at the same time, it's only natural that the fastest ones would arrive first. Not that it makes much difference, though.
Apparently, the Association's prediction was right on target. The mass outbreak this time seems to have happened in the lower section of the middle floors. In other words, the monsters will conveniently stop right where I'm lying down, fiddling with my smartphone on the 30th floor. If it had been on the 25th floor instead, I'd be running all over the place. That would've been a huge hassle, so I hope the Association improves its accuracy or increases its personnel.