Now I'm all for coming to work, I am the one who is always at least 15 mins early. The one morning I was 3 hours late was a very bad blizzard, those of you who don't live in Montana, Wyoming or North Dakota don't really know what that is. I work 50 miles from my home, down a two lane highway. This particular morning there was so much snow and visibility was so bad I had to call my fiance to come pull me out because I had got stuck in a snow drift in the middle of town. After that I tried to make my way down the highway but with the snow coming down sideways in the dark and the wipers not being able to keep up, and the wind piling the drifts in the lane and the visibility so bad I couldn't see the hood of my car through the windshield I turned around and went home. So no, a little snow is no excuse not to come to work. But putting your life in danger is not worth the risk, and thankfully the nurses I work with all understand that as we all deal with it and cover for each other when need be.
EDIT- I waited at home for the sun to come up. Once it was light it wasn't nearly as bad, although it was still bad. Before leaving for that shift I packed a bag, knowing that I had to work the next morning too and there was no way I was coming home in the dark after my shift, then back again the next morning. And I don't care who you are, 4 wheel drive may work great in snow but it does not work on ice. And it certainly will not help you see when the blizzard is blowing in your face, in the dark.