MU likes the Dec 19th-26th period....for much of the LSV he is looking at thread the needle type situation for a snowstorm earlier. LOOOONG READ linked with a snip of it below.
To make a long story short, the strength and orientation of the blocking will have to be "just right" to support a "snowmaker" across southeastern PA. In addition, the position, strength, and evolution of the storm system over Atlantic Canada will play a big role in determining whether or not.. and where.. redevelopment occurs along the East Coast. I won't dive any further into the weeds, but you can now easily see why so much uncertainty exists in the forecast late next week. Predictability and accuracy beyond 3-5 days decrease and are greatly reduced during strong -NAO periods, and numerical computer models don't hande the evolution of storm systems very well. Thus, the forecast beyond 5 days is and will continue to be rife with uncertainty for the foreseeable future.
Special Weather Discussion | Millersville University