If you look at the GFS extended verbatim, the targeted period is after the fifteenth.  There will be a five day milder stretch before that.  Before the end of December, based on many of  forecasts I have seen for December, I will be very disappointed if there is not a widespread significant event, 2-4; 3-6 inch event.  But we have to be realistic here, no one is calling for above normal snowfall this year, and when was the last blizzard in December???  Getting even a few inches east of the mountains in December would be a big deal based on my 50 years of living in the DMV.