Meteorology Overview of Dec 16-20 2009 storm

The December 2009 storm system first developed in the Gulf of Mexico and tracked northeastward right up the southeast U.S. coastline to Cape Hatteras, and then eventually just to the east of Long Island and Cape Cod, where the storm brought blizzard conditions some of the major Northeast U.S. cities. The loop below shows the track of the low pressure center and the radar composite from the morning of Dec 17 through the morning of Dec 20.

This is a "textbook" scenario for heavy snow for our area, with a deepening low passing to our southeast drawing in both Gulf and Atlantic moisture, with fairly deep, cold air in place from an arctic high pressure centered over New England and the Mid-Atlantic area. This is considered a "Miller A" coastal cyclogenesis storm, and is far and away the most common pattern for bringing our region significant snowfall. 

Forecasts for the storm several days in advance were tricky as computer model guidance showed a significant spread in solutions, with many of them forecasting the storm to pass well to the south of the area. About 48 hours in advance, they started coming together with the heart of the heavy precipitation expected to aim right up the Blue Ridge mtns into the big I-95 cities of DC Baltimore Philly and NYC.

Wow this certanly looks interesting going into the next 6-8 days.