When the storm falls down into the Plains to begin its trek either east or northeast, it will naturally provoke high pressure in the Eastern Seaboard. This can be anticipated by the general idea that the low pressure system pushing down will force high pressure to form and push up to equal out the stress inflicted on the atmosphere. Because of this high pressure in the Eastern Seaboard, the storm could very well want to take the northern route and bring heavy snow to the Lower Great Lakes and northern regions of the Midwest, like I showed yesterday. Previous model forecasts enticed the idea of that ridge acting on the storm system and sending it north, but more recent guidance has the ridge being overwhelmed by the low pressure system, which is also very possible.
Considering how model guidance has tended to bring storms to the north just a day or two before the event happens, I'm not willing to discount either solution right now. I think both the northern solution and southern solution have valid reasoning and solid evidence as to why each could happen. The next 48 hours will be crucial to see incoming model forecasts as the storm edges closer to shore.