I think much of it will be in how you word it. If you say that you had to avoid a head on collision you chose to steer off of the road into what appeared to be a fairly flat/smooth/whatever piece of real estate. Because of the buildup of snow you were unable to see the rock, had no knowledge it was there, and as you were confronted with an emergency situation, you made what you thought was the best choice at the time of crisis, and that the accident was not due to negligence on your part, etc etc etc
