This is anomalous cold air, even for the dead of winter. The models will have a hard time handling such dense cold air. I expect to see the models trend much colder as move through this week. I think the models have trended colder in the 3-5 day range for the last 60 days. The problem until now has been that there's been little cold air to work with. The cold air coming now will be a whole different animal. Tapping regions with dew points in the teens (since back in early December) is totally different than tapping regions with dew points below zero.
I think if nothing else, the dense nature of the cold air will lead to alot of ice, and not just in CAD areas.
TW