Rarely do flips happen during holidays, but it does happen. Fourth of July is a popular time. The day after Christmas is another. New Years Day is one. But Memorial Day, though the unofficial start of summer, seems a rare time to flip formats from my years of experience.
Further, the Spring Arbitron is underway, as it will for the next month (June 27th.)
Traditionally, format changes &/or flips are made either on Wednesday, the day before first "official" diary week recording (in each of the 12 week rating period) if not on the very first day of any given "official" diary week (Thursday.) A PPM "diary" is the same, from my understanding, as it pertains to "official" recording of entries on Thursday.
Take a look at recent flips in San Francisco and New York and you'll see that.
'YSP may just have to wait out this book to see.
I'd be surprised if 'YSP changed this weekend. Pre-season football time would be a good time ... right after the book is issued in the next to last week of July.
That also broadens the speculation of what CBS really wants or "can" do with 'YSP and other Free-FMs. In Philadelphia, it would also give them time to re-establish 'YSP before the Fall book begins.