Here at Umich, you'll experience a brief fall, and then the rest of the year is winter.
Winter isn't wet so much as it is cold with some variation of snow, ice or slush on the ground most of the time. Any backpack will be fine. When it's falling from the sky, it's usually snow, which brushes off. What you really need are a warm winter coat and insulated waterproof boots or shoes. A heavy down parka will last for years and you'll need it. If you'd like to do any long walks on our icy sidewalks or the B2B without falling, especially December through February, when they're most treacherous, think duck shoes and consider getting cleats, like these.
You could try Yaktrax - the things that slip over your shoe to give you traction on ice & snow.