Sandwiched around this cold period will be a mild, but variable beginning and end to meteorological winter. If you remember the winter of 2008-2009, there may be a lot of similarities to that winter in terms of brief, significant warmups in advance of storm systems that bring rain, followed by a cool down, with a yo-yo pattern of sorts around a cold January. This winter may shape is in similar regard -- early and mid December featuring mild but variable weather (there will be some cold shots mixed in with a few warm days) before the pattern loads up with colder air for the latter half of December and the beginning of 2012. The holidays will likely be colder than average, with the coldest weather of winter occurring just after the New Year.
In terms of snowfall, we're projecting slightly above average snow for the region this winter -- between 24 and 29 inches overall. One can't deny the trend towards snowier winters of late but Philadelphia has never had three consecutive winters of more than forty inches of snow. I'm sure the snowstarved would love to see it -- unfortunately, I don't think it happens. Most everyone ends up a bit above average on the whole -- nothing dramatic for the winter but the suburbs should get to around 30" this winter, with the Lehigh Valley getting a shot at 40" of snow this winter if everything breaks right and the Poconos having a shot at a 55-60" snowfall winter. Not bad...for some, not as great as last winter, but the odds lean towards slightly above average snow. Snow is always the big wild card though!