I read somewhere that AAA Motor News listed this as a new ski area in 1962. On Feb. 3, 1966, it was listed in The Cass City Chronicle’s AAA Guide to Winter Sports Fun in Michigan as having 6 slopes and 2 tows with cross-country trails and tobogganing. On Thu., Dec. 10, 1970, the same paper’s AAA 1971 Winter Sports Fun List had the same information.
Thunder Bowl was 22 mi. northwest of Manistique on Thunder Lake. I see several references to it on the web as a former ski area now used as a sledding hill, and on the satellite and contour maps it looks like it may have been on the north-east-facing ridge of a hill just north of Thunder Lake.
If you have any recollections of lift-served skiing at Thunder Bowl in the UP, please post them in a comment here or send them via the instructions on the About MILSAP page,