A wave along an exiting cold front will bring a period of light snow to parts of southeastern Pennsylvania on Wednesday that will wind down after sunset. Most areas will see little to no accumulation (<2”) from this snow, but it will likely be the first measurable snow in that portion of the state. Temperatures will be a bit cooler than normal on Thursday with afternoon highs mostly in the 30s with a mix of sun and clouds. Friday will be slightly warmer with highs in the upper 30s to mid 40s. By Friday evening, a storm developing in the Gulf Coast will begin moving northward along the East Coast. Southern Pennsylvania will see precipitation first by sunset on Friday. Periods of rain will overspread the state overnight into Saturday morning. Parts of central Pennsylvania, where colder air may stubbornly remain for a longer period of time, may have a wintry mix at the onset of precipitation. The storm will exit the region by Saturday night as rainfall comes to an end. Behind the storm, cooler air will arrive and lake-effect snow showers in northwestern PA will ensue through Sunday afternoon. Monday will likely remain dry before another storm threatens the area later Monday into Tuesday. At the moment, precipitation type is difficult to determine but parts of the state are at risk for a prolonged period of wintry mix or accumulating snow. In the longer range, temperatures will likely be milder than average through the start of the new year while precipitation will be slightly above seasonal levels.
Source : psu.edu