Synopsis
Another accumulating snow event is possible during the day Sunday this weekend, with accumulations somewhere in the 2-4″ range currently most likely. If this storm tracks a bit closer to shore, we could see totals more in the 4-6″ range. The timing of this storm is much faster than the previous one, with onset of snow early in the day Sunday, lasting potentially through the early afternoon hours. As a weaker system, without as strong a high pressure system downstream, winds should also not be as robust as with the Monday storm.
Weather Prediction Center 48 hour 50th percentile snowfall accumulations for the NYC metro region ending 1AM Wednesday 
Weather Prediction Center 48 hour 90th percentile(median) snowfall accumulations for the NYC metro region ending 1AM Wednesday 
GEFS ensemble plumes for total snow accumulation at KLGA. The mean here is about 4″ with a significant number of ensemble members showing lower amounts. 
SREF ensemble plumes for total snow accumulation at KLGA. The mean is about 2″, with similarly large numbers of ensemble members showing lower amounts.
Forecast Details
At the Surface
Low pressure developing over the Southern Plains will emerge offshore of the Carolinas later tonight. This surface low will strengthen modestly as it tracks quickly northeast. Current thinking is that the storm track takes it outside of the classic 40ºN/70ºW benchmark that leads to maximized snowfall for nor’easter type systems in this area.
ECMWF “Euro” model 1000-500 mb pressure, thickness, and surface precipitation/type at 1PM Sunday. 
GFS model 1000-500 mb pressure, thickness, and surface precipitation/type at 1PM Sunday. 
NAM model 1000-500 mb pressure, thickness, and surface precipitation/type 1PM Sunday. 
Weather Prediction Center storm track forecast.
850 mb Level
At this level of the atmosphere, it’s apparent that this storm is much less of a headline maker than Monday’s snowstorm. It’s evident from various models that while there should be enough moisture to sustain precipitation, the winds at this level are not forecast to be anywhere near as strong as on Monday. The lack of a truly robust low-level jet will make for an overall slightly drier scenario.
ECMWF “Euro” model 850 mb winds and relative humidity at 1PM Sunday. 
GFS model 850 mb winds and relative humidity at 1PM Sunday. 
NAM model 850 mb winds and relative humidity at 1PM Sunday.
500 mb Level
Unlike the last storm, the 500 mb level flow for this upcoming storm is more progressive. This will lead to the storm moving faster through the area. One notable factor contributing to the potential for a decent storm this time is that there will be a negatively tilted trough at this level, indicative of a maturing and deepening low. This feature will serve to enhance divergence at this level and induce surface lift in response.
300 mb Level
As was the case with Monday’s storm, a curved jet streak should set up just north and east of this storm’s surface low. The entrance region of this jet streak should allow stronger divergence and enhanced lift as a result.