Still a tough forecast
For southern areas, this appears to be roughly a 48 hour event. For most of the rest of the region it appears to be 24-30 hour event. Bust potential still looms large in many facets of the forecast, especially the Tuesday part. I'll give it my best shot here, but confidence is low.
Stage one: Sunday to Monday 7 PM
The storm will be slower in arrival, so for those folks hanging on for an extra day of family time before you head home, you lucked out. Conditions will go downhill over western New England this afternoon. The first wave of flakes should arrive in southern Maine by around early evening.
The storm stalls and spins east of the benchmark 40°/ 70° through the day on Monday. Dry air to the north shuts out ski country and the north. High pressure associated with that dry air keeps precipitation confined to southern areas from roughly Fryeburg to Rockland south through early Monday evening.
The heavier amounts of snow are to be in York County. Due to the stalling of the storm, I remain concerned that warm air will sneak in aloft and form a TROWAL (TRough Of Warm air ALoft) and bring the threat for sleet. There is always the chance for a coastal front to develop, but the strong northeast wind may limit that chance to the islands and immediate shorelines. Add the wind that could gust 20-30+ mph, all the ingredients will make for tough travel in the most populated region of the state.
Stage two: Monday 7 PM to end of storm
So this is where the forecast gets real complicated. I've mentioned previously issues with the lack of stacking between the surface low, mid-level lows and the upper low which is causing the conundrum of mixed forecast ideas as a result of various model solutions. Where the atmosphere may pull together appears early Tuesday. As the upper low moves into capture the surface low, an new surface low forms and then potentially heads north in the Gulf of Maine towards DownEast areas before moving east.
With that idea, this is where the rest of the state gets in on the precipitation, and will potentially cause issues with the morning and evening commutes for Bangor and points north and west.
The storm departs and precipitation shuts down Tuesday night. Strong wind may cause blowing an drifting of snow, and potentially some power outages.
Day two of the storm brings additional accumulations to southern areas, and brings most of the rest of the state a decent amount of snow through Tuesday evening.
An uncharacteristic snow total