Exactly: I have some experience driving in snow and I've certainly made a few big mistakes that I'm pretty sure a computer (that would have a much better sense of available traction) could have avoided. I can also easily imagine sensors that can see through headlight-lit falling snow better than a human.

"Will be"? Probably. Right now? Probably not.

Ice and snow are real issues for, say, the Google car. Driving at night is pretty good because its sensors can still see things better than the human eye.