The NAM and GFS models were in agreement on a heavy precipitation event associated with a rapidly deepening cyclone over the mid-Atlantic area from the surface through the mid-troposphere.
The GFS model was forecasting the center of low pressure farther northwest than the NAM, with its maximum of precipitation also farther northwest.
Antecedent conditions were extremely favorable for flooding.
Factors forecast to be favorable for heavy precipitation included a rapidly deepening cyclone, a 50 kt 850 mb southeasterly jet, strong theta-advection, strong isentropic lift, high precipitable water values, and strong frontogenesis co-located with reduced EPV.