I think they are working on “record for this date,” so it is possible to have a record on this day that doesn’t equal a record on another. day.
Hence the qualifier at the end of my original post (that it might be for the speed at which it occurred). I did read the article and they claimed that superior had never iced over, which isn’t true. I also provided a link to the article I referred to in my next post, you should check it out; it’s worth the two minutes it takes to read anyhow.