Quite the detailed disco from Mount Holly on this weak little pos system that is our best hope for snow to this point and going forward(sadly). We talking.. Dynamic cooling.
Snippet from the afternoon AFD-
An initially cool and dry airmass in place across the area will be overtaken by weak warm advection into Sunday evening as heights begin to fall and broad upper diffluence spreads over the area. Light precipitation is expected to spread into the region during the evening hours, generally from southwest to northeast. Given the subtle and broad forcing mechanisms and marginal thermal profiles with this system, confidence remains fairly low on exactly how the precipitation types (rain or snow) and amounts will evolve. That being said, current indications in the guidance are that there will be a period of snow across portions of the area, especially at the onset of precipitation before the warm advection begins switching the precip type over to mostly rain from south to north into the urban corridor.
Precipitation is currently expected to start mainly as light snow near the Philly metro and mainly as light rain farther south across a line from near Kent Island to Dover to Cape May. However, if any banding or stronger intensity of precipitation occurs to the south, some will probably snow mix in early in the event farther to the south near the aforementioned line due to dynamic cooling. The thermal profiles will support a rain or snow precip type, and little to no sleet or freezing rain is expected. The precipitation may come in two waves, first during the evening and a second overnight during the predawn hours. In any case, the thermal profiles will begin to support mainly rain in the Philly metro and south with rain and snow possible farther north into the early morning hours. Although again, any heavier/banded precip that develops could change rain back over to snow due to dynamic cooling. This could lower surface temperatures just enough for additional light accumulation in grassy and elevated surfaces. North of the Philly metro and I-95 corridor, and especially north of I-78, the biggest question is how far north does the accumulating precipitation get. The antecedent airmass will be fairly dry, so as forcing decreases to the north, the QPF should as well. We currently have the higher QPF near the Philly metro and areas to the south generally ranging from a tenth to two tenths of an inch. We are currently forecasting less than an inch of snow for the entire forecast area for Sunday night. If more intense or banded precipitation develops near the Philly metro or areas to the north, snow duration and thus amounts may be locally higher than we currently have advertised.