As cold air spills into the commonwealth on Friday, the remnants of lake effect clouds in northwest PA will fade away. An overcast quickly builds in overnight in advance of a winter storm that will bring accumulating snow and sleet to many on Saturday, as well as run the full gamut of precipitation types. After an arctic cold front brings snow showers and squalls to western PA overnight into Sunday, areas downwind of Lake Erie will be dealing with lake effect snow through Sunday evening. Mostly cloudy skies and flurries stay parked over northern and western portions of the state on Monday, with southeastern areas seeing considerably more sunshine. Skies will become mostly sunny for Tuesday.