How does the author use foreshadowing in Rats Saw God?

In the section entitled, San Diego, Senior Year, Sarah, who is typically very levelheaded and personable has an outburst at the table, directed at Chuck. This is uncharacteristically confrontational for her and foreshadows later developments in the novel. The apparently innocuous rock concert also sets up a series of events that will dominate Steve's life over the coming months, which ironically contrasts his decision to remain uninvolved.