Up in the Franconia/Twin/Crawford area over the holiday we found 4-6 inches of light, fluffy snow atop ice, an incredibly slippery combination.
Traction was mandatory on mellow trails (microspikes needed on A-Z) and seriously needed on steeper trails (trail or full crampons needed on KRT tramside). In some places, even the rocks on the sides of the trail that you might use as a handhold were covered with a half inch of clear, solid glaze ice.