I just woke up. I was supposed to be on the train right now.
in a rapid succession I called my dad to tell him I wasn't on that train, and then checked Amtrak's website for the next one's departure time. 12:30. Available, but not for online booking. All of the other trains to Seattle today were booked up as well.
I called and it's my lucky day—I got the last seat. I rechecked the train on Amtrak.com and it already tells me that it's now a full train. Splendid. Seattle, now I will see you at 4:00.