Millersville's take:
In the short term, I'm keeping a close eye on Thursday night/Friday as our best chance of receiving a meaningful, widespread snowfall. However, the disturbance of interest is still hundreds of miles off the coast of the Pacific Northwest, so taking a shot at predicting potential snowfall totals at this distance is a fool's errand! In fact, there's still a chance that we receive nothing more than a few flurries. The good news is that we likely won't have to deal with precipitation-type issues, so anything that does occur will be in the form of snow. At this point, my biggest concern is that the disturbance remains so weak and strung out that any meaningful snow stays to our south or doesn't even develop until it's "too late in the game" for the mid-Atlantic. What we do have going for us this time is that the ridge axis in the West is located very close to Boise, Idaho.. an ideal location for snowfall in southeastern PA. If you want several inches or more of snow, then you want the ridge axis to be stronger and more amplified than what's currently projected. In general, a more amplified ridge results in disturbances over the Ohio Valley and mid-Atlantic intensifying more rapidly. These disturbances also tend to "dig" more, allowing them to draw Gulf- and Atlantic-moisture northward into the colder air. Even if this does occur on Thursday night and Friday morning, the system will be moving along so quickly that anything more than a light-to-moderate snowfall is highly unlikely.