Between June 25 and Aug 10, the daily high max at MDT has been 100 or over 30 of the 47 days so not at all uncommon. Some of those were same year/multi-day events but I am sure there are other days where it has hit 100 more than once on that day in the past. I bet someone has exact stats but would say its not at all a "rare" event.
I mentioned it yesterday but really seems like Harrisburg and East/South score in these types of patterns. Not everyone but out west there is very little scoring the last couple years. Maybe that changes this week.
Right now I cannot find a model to latch on to. They are all struggling. GFS still doing ok on pattern recognition but is doing terribly with apparent weather on the day of the event.