Giving Packing The Cold Shoulder

I am headed to Detroit next week. That's right, this AZ girl will be venturing willingly into cold weather. I haven't gone totally crazy, (well, the jury is still out on that), because I have planned well for the freezing temperatures. (I have been to the 'rents origins in the midwest during 0-10 degree temps, before, so I am not completely green). I already have too many sweaters and scarves and gloves, so I bought a down jacket and rain boots and called it a day.......except that I just checked the weather again and now it will be raining/snowing while I am there! This throws a whole new wrench into the gears and now I am completely second-guessing my preparedness!

This is what I was going to wear:

Calvin Klein Hooded Satin Down Coat. (It is longer on me, which is surprising since I am tall-- it covers the bum). And it's on super-sale if anyone needs a new coat!


Jeffrey Campbell Voom Rain Boot. These are pretty sturdy and comfy (I tested them last weekend when it was rainy here) but not lined or anything, so there will be a lot of layered sock-action going on...

Throw in some lined gloves, scarves, long underwear, and a flask (kidding...maybe) and I feel prepared...but the rain...argg! I guess I just need a little advice from you snow-pro's out there: Do I need a waterproof coat? Can I just bring an umbrella? What in the heck is the difference between "rain/snow" and "snow showers"? hehe

Any tips would be greatly appreciated! Now I am off to finish my packing list... (It's going something like: toothbrush, make that two flasks, wool scarf...) Happy Friday!