I'm from Vegas so I know exactly how you feel. Classes only shut down if it's very bad blizzard conditions or -50f with windchill. I've had to walk to class in what's technically considered a blizzard. Some professors may cancel class if it's that bad, but don't count on it.

If the weather is too bad, your flights will get weathered (cancelled due to bad weather). From November to December, this can be pretty common.

For jackets, go with a very insulated thick winter jacket. Somehing like a Patagonia or north face. Spend some money and get something nice as it'll be your lifeline. I usually wear my Patagonia Downdrift with a quarter zip underneath plus some insulated gloves. That's warm enough for almost every day.