Jumping back to the Euro Seasonal, I would definitely not give up on December. The only free maps the Euro site offers are world and N. Hemisphere views. As such, attached are the World 850 temp ensemble mean anomaly maps for December and January. Both months have us in the normal range with December closer to slightly AN and January closer to slightly BN.
Thus, we could definitely score in December, mostly likely a single event like 12/82 where BWI had a coastal that dropped 6.7" with Biglerville at 2". And despite that event, BWI was still +3.4 degrees AN for December.
Finally, also attached is the 500mb anomaly for 12/82 that was butt ugly but still didn't prevent a coastal.