These 2 cases support work by Albright and Cobb (1995 and 1996) that described synoptic patterns favorable for heavy snow in Norfolk, Richmond and northeast North Carolina. In the past 7 years, most heavy snow events in the AKQ CWA were associated with upper level impulses that entrain moisture from the Gulf of Mexico, and whose upper level deformation zone tracked through Virginia.
Upper impulses and jet streaks within strong west to east upper flow can produce significant snow (>4") in northeast North Carolina after interacting primarily with Atlantic moisture, but these types of systems do not typically produce significant snow in Virginia.
Detailed data analysis is just one element of effectively diagnosing the state of the atmosphere prior to forecast model evaluation. Events 1 and 2 featured northern stream systems that tracked southeast, out of Canada, and interacted with Atlantic moisture.
Identifying upper and low level features in satellite imagery and upper air analyses, can provide valuable information on movement and evolution of weather systems.
Recognizing the upper level pattern along with knowledge of upper jet dynamics, and their relationship to thermal/moisture advection and upward vertical motion, can aid a forecaster in pinpointing the areas of greatest threat for significant snow.