Latest NAM FOUS data just became available. This will be mostly an ice storm rather than a snow event.

Temperatures in the upper atmosphere become too warm for snow before daybreak.  Light snow starts after midnight but changes to sleet and freezing rain by daybreak in PHL.

Heavy freezing rain, likely with temperatures remaining near or below freezing at the surface, continues until late morning with a significant “cold air damming” effect.  A significant ice storm is possible with heavy precipitation causing dynamic cooling, prolonging the freezing rain event.  

Difficult travel during much of the morning, especially north and west of the city.  Temperatures rise above freezing by the late morning or early afternoon as the precipitation tapers off.