A deep trough, or dip, in the jet stream winds aloft will mean cold air spills into the Eastern two-thirds of the Lower 48 next week. Remember that the jet stream is the fast river of air, high in the sky, that steers storm systems and also separates cold air to the north from warmth to the south. A pronounced southward dip in the jet stream over the Eastern United States will come in response to a large storm center developing in Central Canada, chock full of cold air. As the jet stream buckles south, a solid chunk of that cold air will drop south, making for much colder than normal conditions throughout the Northeast, including New England.
At the same time, a series of upper level disturbances moving through the cool air will likely mean a number of showers in the Great Lakes region during the forecast period, and with much colder than normal air in place, some Great Lakes snow showers are entirely possible. Similarly, some snow showers may occur in the higher terrain of Northern New York and Northern New England, particularly at night. Farther south, though some guidance indicates the potential for a swath of snow to fall beginning to middle of the week, that seems unlikely given the building anticyclone (high pressure) into the Appalachian Mountain chain.