6 PM Update: The afternoon model run is consistent with the morning one in showing a low pressure area tracking to the south of the area and bringing Washington snow on Christmas.
See here for an example of how snowfall amounts are not necessarily correlated with temperatures.
The eyeball-hungry low-fiber WaPo has pimped the "s-word" in
The National Weather Service, while carrying a 50% chance of Washington snow on Christmas, is being respectful of the uncertainty at the limits of practical predictability:
LATEST GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT WITH LOW PRESSURE IMPACTING THE REGION SOMETIME FRIDAY AND SATURDAY. THERE STILL REMAINS A GOOD DEAL OF UNCERTAINTY WITH THE TRACK AND DEVELOPMENT OF THE SYSTEM. IF THE LOW TRACKS CLOSER TO THE COAST...SIGNIFICANT SNOW IS POSSIBLE DURING THIS TIME. HOWEVER...IF THE TRACK OF THE LOW REMAINS WELL OFF THE COAST...SNOWFALL WILL BE LIGHT. ALL INTERESTED PARTIES SHOULD DEFINITELY STAY APPRISED OF THE LATEST FORECASTS AS WE GET CLOSER TO THIS POTENTIAL EVENT.The map to the right shows one major model's interpretation of the surface weather for 7 pm, Saturday, December 25. It has a strengthening storm off the Mid Atlantic coast, with snow over much of the DMV (DC/Maryland/Virginia). If interpreted literally (a serious risk at the range of 5 and a half days), it would generate a total for the event of about 3-5" of snow in the region, with the larger amounts in the southern and eastern portions.
The graph shows snow depth on the ground in Washington on Christmas for each year since 1929. By the way, the 7" last year, while tying the record for the period, had completely disappeared the next day. Note to Ice Ager Linkbot Tom N: If you can find a trend in that data, you deserve to beat out Fred the Singe-r for the Nobel Prize in Cherry Picking.