Oh, look, a lightning! There it was, on the left! Oh look, another one, to the right! Whoa, that was a big one! Right in front of us! And another one, behind! Wait… If there are strikes in all four directions, what's stopping one from appearing right above us?
When your survival instinct starts asking such questions while you're standing out there on a rooftop, taking pictures of a storm, you know it's a bit late to the party.