Synoptic-Scale Features Common to Heavy Snowstorms in the Southeast United States

Abstract

Eighteen heavy snowstorms in the Southeast are examined to determine the synoptic-scale features common to these storms. Storm-relative composites in the temporal domain are created by assigning a ''zero hour'' to each storm based on the time of initial snowfall at Asheville, North Carolina. The composites indicate the importance of warm air advection (isentropic upglide) in producing upward motion within these storms. Of secondary importance in producing upward motion are the right entrance region of an upper-level jet streak, diabatic processes, and cyclogenetic lift. The composites also indicate that moisture is drawn off the Gulf of Mexico to feed these storms, while Atlantic moisture pools at low levels and may inhibit snowfall in the Piedmont region by limiting evaporative cooling. The surface cyclones, which deepen over the Atlantic near the Carolina coast, appear to play a small role in the development of Southeast snowstorms but often lead to heavy snowfall in the Northeast.