The Eta and other models were forecasting a significant precipitation event early on the 6th, with a significant portion of the precipitation over northeast Pa forecast to be freezing rain.
The precipitation would be driven by persistent favorable dynamics in the right rear quad of an upper level jet, including a strengthening 850 mb southerly jet and unusually high values of precipitable water.
A significant northerly agesotrophic wind component was being forecast below 900 mb during the event.
1000-900 mb easterly low-level flow was forecast to be associated with near neutral temperature advection through 12 UTC, while strong warm advection and upward vertical motion was forecast aloft.
The ageostrophic wind appeared to be in response to strong frontogenesis.
Surface pressure falls were forecast over the eastern Great Lakes in association with deepening low pressure in that area. High pressure was forecast to retreat across eastern New England.