By doing more secondaries
😛 Not sure yet actually. I'm still a bit in the

phase right now.
You will likely have three interviews:
-one with a member of the admissions team, who has access to the entirety of your file
-one with a faculty member, who has access to most of your app but not everything (I forget the particulars)
-one with a student (if you're interviewing early this will likely be a MS2, MSTP, or MS4 student, and if later could also be a MS1), who has access to your primary but not your secondary or your numbers (GPA/MCAT)
I say "likely" because if, for whatever reason, the office is unable to find student interviewers for everyone scheduled for that day then no interviewees for that day will have student interviews. This is very rare, though.
As far as preparing for the interview, my biggest piece of advice is to think about why you're interested in coming to Pritzker and why you think you would benefit from training here specifically over any other institution. In my experience, applicants that are best able to do this have the most success. What can Pritzker offer you that you think will make you a great physician? How (or will) you continue to pursue your interests here? What sorts of things do you think you'll take advantage of if you end up being a student here? Beyond that, being familiar with your app and being able to succinctly summarize your experiences and why they were important to you will be helpful. Be yourself!
The interview day is very friendly, and hopefully you'll get the sense that you are truly welcome to campus and that the admissions staff is happy to have you here. They really do want to get to know you, and the interviews will be low pressure and driven with that goal in mind. Of all the interviews I attended I thought Pritzker's was the most enjoyable, and I was surprised at how well they treated us as applicants.
As far as weather, expect warm and humid. In August I would say 90s on a warm day, 80s or even 70s otherwise.
Hope that helps!
Sent from my Nexus 7
Edit: Sorry that the quote above got messed up - Tapatalk goes a little stupid sometimes. My response was directed to Farmerboy.