I don't know if much of tonight's wave makes it very far east of the mountains, but from I-99/US 220 below I-80 westward into the Laurel's region this is starting to look like a surprise event considering what CTP has in their winter products at the moment compared to the models today. Early HRRR looks into this event are pretty robust, with more northern extent than the NAM and high end advisory snow amounts Cambria/Somerset (Laurels). Models are generally supportive of that region (and even into the surrounding counties) seeing potentially an advisory event "on paper". Temps are warm today obviously, but dew points are very low.. so I don't think getting a timely changeover will be hard once the heavier precip moves in.
Given how warm it has been and virtually no preceding or entrenched true cold, this is going to be very springlike and play out more like an early April type wave.. with accums mostly on the grassy surfaces and it might take awhile to actually get anything going on the ground. But timing of this thing overnight is going to help. I think any road issues that pop up will be reserved for the higher Laurel's. Somerset County looks to be the PA place to be for this, and I wouldn't be surprised if parts of that county sees close to the amount the short term guidance is putting out snow wise. I don't think the precip makes it past the the mountains to the Sus Valley heavy enough to make for any accums, even if it does actually mix or changeover. Will have to see how the swath tracks, as it could run the turnpike or perhaps make it a bit further north as the HRRR is suggesting. A decent amount of guidance says I get my biggest snowfall of the season tonight, we'll see lol.