How does the author use foreshadowing in the novel, The Weight of Blood?

When Kenny stares at the long lifeline he has on his hand, it both symbolizes and foreshadows the fact that he will be one of very few people to survive prom. Since the reader knows all along that most people will not survive, this mention of the lifeline brings up the question of whether Kenny will survive. In the end, Jackson does not say what specifically happened to Kenny, but it can be assumed that he did survive and he escaped with Maddy.