A major ice storm occurred over the higher elevations of northeast Pennsylvania on January 6, 2005.
A moderate snow event also occurred across northeast Pennsylvania and southern New York on the 5th and 6th.
The event occurred when a strong low-level jet developed in the right rear quadrant of a persistent upper level jet streak. The low-level jet overran a layer of cold air based at the surface.
A low-level ageostrophic northerly flow associated with strong low-level frontogenesis helped to offset the diabatic warming due to freezing typically associated with icing events.