SYNOPTIC-SCALE FEATURES COMMON TO HEAVY SNOWSTORMS IN THE SOUTHEAST UNITED-STATES

Eighteen heavy snowstorms in the Southeast are examined to determine t he synoptic-scale features common to these storms. Storm-relative comp osites in the temporal domain are created by assigning a ''zero hour'' to each storm based on the rime of initial snowfall at Asheville, Nor th Carolina. The composites indicate the importance of warm air advect ion (isentropic upglide) in producing upward motion within these storm s. Of secondary importance in producing upward motion are the right en trance region of an upper-level jet streak, diabatic processes, and cy clogenetic lift. The composites also indicate that moisture is drawn o ff the Gulf of Mexico to feed these storms, while Atlantic moisture po ols at low levels and may inhibit snowfall in the Piedmont region by l imiting evaporative cooling. The surface cyclones, which deepen over t he Atlantic near the Carolina coast, appear to play a small role in th e development of Southeast snowstorms but often lead to heavy snowfall in the Northeast.