A deep jet stream "trough" - or dip in the jet stream winds aloft - is likely to set up in the Eastern United States by the middle of next week. This buckle in the jet stream winds - the fast river of air high in the sky that steer our storm systems and separate warm southern air from cold northern air - favors a merger of northern and southern energy, and a clash of warm and cold air, thereby favoring storm development. With the jet stream dipping south toward the Gulf of Mexico, ample Gulf moisture would be available to fuel a growing area of precipitation with the storm, and with cold air in place for New England ahead of the storm, snow would be possible to start, then any rain/snow line would depend upon storm track.
Obviously, from several days out, it remains to be seen whether this storm comes to fruition, but there are a few things going for it, including both the jet stream configuration, and the fact that a slug of warmer air is heading into the cold Northeast air at that time. Incidentally, that potential Thursday storm looks to be the start of a warmer burst of air with temperatures reaching 35-40 by next weekend.