Thinking of doing a trip to California from NJ with some stops along the way. We would have a Month so we can take our time along the way. We would be using our Audi Q5 with All season tires. We probably can only do it in Jan-March do to commitments. Curious how bad is the Northern route. Are there good weather apps to look at as we could head south if weather turns bad. Are the National parks open in the winter?