Something I'm watching is how long of a gap there will be between first freeze at RFD and ORD. Rockford had it on 10/8, so it's 23 days and counting. On average, it's more like 2 weeks between first freeze at RFD and ORD, but they have done it on the same day in some years.
Perhaps more amazing is that Rockford has been AOB freezing 9 times. It seems like it would be pretty unusual for Rockford to get out to a 9-0 lead, but I haven't checked into that.