At Green Ridge State Forest in western Maryland, the rule used to be that you could set up at any site, then go register the following morning if it was after hours. So we planned on doing just that. It was Winter, with about two plus feet of snow on the ground. After shoveling our way in we weren't about to go drive to the ranger's station so we settled in for the evening.
The following morning, we noticed the temperature was rising and a very light rain had begun to fall. Then we saw the snow start to turn gray. Time to get out! NOW!
We quickly grabbed everything out of the campers that we could, threw it all up a bit of a hill, jumped in the trucks and rolled out - just as the snow melted into a river that wiped out the entire valley we'd been in. As it turns out, it wiped out more than just a bunch of the forest - several towns were under several feet of water.
As it turns out, the park had been closed because they were expecting trouble. The rule used to be that you could set up at a site if you got there after the ranger's station was closed and go register in the morning. Maybe because of us, that rule was changed. There are signs all over the place that say pre-registering is mandatory, even if after hours. They now have a self-registration system in place for that.
Still young and stupid, even in the middle of the panic, we stopped to snap a picture as the water was still rising.