GOING ANYWHERE THIS WEEKEND?
GOOD LUCK WITH THAT.
THU 12/17 UPDATE: The current US Hazards Assessment shows potential for a variety of significant winter events this weekend across two-thirds of the country, just in time for the arrival of... winter. Like it or not, most of the U.S. has entered a long duration period of cold and stormy weather that will extend into Christmas weekend. 
THU 12/18: MID-ATLANTIC STORM SUMMARY FOR FRIDAY-MONDAY
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Friday: Wintry precip stays out of central Maryland, with exception of areas along PA Boundary, northern Harford and Cecil. Most of PA will experience snow and sleet mixed, changing to freezing rain then rain, and by nightfall turning back to light snow before ending. Central and Northern PA into New York including the city should receive heavy snow with amounts ranging between 6 to 12 inches.
Saturday: Not much of a rose between two thorns, as scattered light freezing drizzle is expected in PA, with mixed light rain/sleet in MD. As evening approaches, a high pressure system in New England will wedge in cold air at the surface in advance of the next system. Light ssnow moves in overnight across most of West Virginia, central and western MD, Northern VA.
Sunday: Everything goes. Most of us in the Mid-Atlantic from west Virginia to New Jersey and everywhere in between will wake up to snow, mixing with sleet as the day progresses. A large area from the Philly suburbs south to Washington will experience a long duration period of light snow, sleet and freezing rain from mid-morning to early evening. There may even be a lull of saving grace for travelers Sunday afternoon, as a secondary low forms off the DelMarVa coast. Precip may end briefly as rain before colder air filters in behind the secondary, turning any remaining moisture over to light snow Sunday night.
Monday: Whatever fell on Sunday will have frozen over with overnight lows reaching the upper teens. This has potential to cause school and travel delays Monday morning. Temperatures may never climb above 32 across the region, and cold north winds will prevent melting. It'll be one of those rough "gotta scrap off the car" type mornings.
WED 12/17 UPDATE: The New England ice disaster was the start of several rapid fire storms occuring every few days, preceded by false warmups, followed by progressively colder conditions. Dare I say it, but if snow accumulates from any of these storms, the temperatures going into early next week will be cold enough to provide many of us with that elusive, highly-sought, nostalgic, holiday weather-related event. The Sterling, VA NWS is already beating the storm drum with this in their discussion:
" KEEP YOUR EYE ON LATE SAT NGT INTO SUN. SIG WINTER EVENT MAY BE UNFOLDING DRG THIS TIME. GFS IS GETTING CONSISTENT IN SHOWING A VERY CLASSIC PTN FOR WINTER WX IN THE METRO AREAS AND POINTS W. IAD FCST MAX TEMP OF 33 IS DOWN A DEG VERSUS YESTERDAYS MEX MAX GUIDANCE FOR SUN AND IT WILL START OFF BELOW FRZG TO START THE EVENT. 850 MB TEMPS START THE DAY AT MINUS 7 IN THE MTNS WITH SFC SYSTEM FCST OVR KY AT 12Z SUNDAY. 2NDRY LOW THEN BEGINS TO FORM ALG THE CAROLINA COAST. AGAIN...STAY TUNED. IF YOU DON'T LIKE WINTER WX...MIGHT BE A GOOD TIME TO CALL YOUR FAVORITE AIRLINE AND GET THAT TICKET TO MIAMI."
For archival purposes, what was originally said on Thursday, 12/11/08 regarding the upcoming pattern:
" I have reason yet to "just believe" in the potential for a major snow and ice event for the Mid-Atlantic and Northeast corridor before December ends. Although I originally targeted the first week of December as the likely period, a slowing of the pattern progression has delayed this possibility by 2-3 weeks. That places the next period conducive for measureable, significant snow (greater than 4") or ice (greater than 1/4") to December 17-25."