NWS is somewhat poo-pooey for Sunday but do mention plumes. Will probably up their game if 12Z runs show any kind of consistency on a threat.
Precipitation should taper off Sat night as the front exits the
area. However, some model guidance forms a wave of low pressure
along the slowing front. If this were to occur, a second period
of snow/rain is possible over Southern PA Sunday. The 12Z EPS
plumes only support POPS in the 30pct range over Southern PA.