Seen folks talking about truly upper echelon potential......you need arctic air around to achieve that, at least in January, anyway....I'm not referring to just temps and I don't necessarily mean P-Type issues. Its tough to pull off a true upper tier systems in mid January without arctic air.
You have more margin for error at peak climo with respect to temps and reasonably large systems....but good luck pulling widespread 20"+ in mid January without arctic air. I'm not complaining about it...just stating an opinion.