I know there's been alot of posts with the "storm vs. no storm" but I don't really think that is the case. The GFS has always had something, its just a matter of where the baroclinic zone resides. There certainly will be a wave of low pressure which develops within the South which moves off the Southeast coast and then rides northeast along the zone. If that zone is further northwest, we increase the potential for snow. If it is further southeast then we decrease the chance.
But I think there are other factors as well. This is now 3 winters in a row we've seen these significant Arctic blasts penetrate deep into the South with potential for some significant wintry precipitation within the South. At least from my experience the GFS has done handled these well, particularly with precipitation forming along it. The NAM seems to have a better handle.
Not sure how much of an influence this has on things but the GFS also tends to get way too aggressive with the cold (at least MOS does). So it is possible this is one reason why the GFS seems to have a SE bias in these situations.