A Case Study of a Prolonged Sleet Event: 16-17 February 1987 and Climatology of Sleet Events for North Carolina, 1949-1989
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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Winter storms in the southeastern region of the United States have the potential to produce widespread regions of mixed and frozen precipitation, with serious economic and social ramifications. Due to the relative infrequency of these storms, most southeastern states are ill prepared to deal with their effects. Thus, increasing the need for accurate and timely forecasts of the type and duration of precipitation in this region. An investigation was undertaken of an unusually prolonged sleet event that affected North Carolina on 16-17 February 1987, to identify the synoptic and mesoscale features that governed the formation and duration of the frozen and mixed precipitation. Sleet was observed from Kansas eastward across the Appalachian Mountains to the western third of the coastal plain, with accumulations of more than 20 cm occurring in the eastern portions of the Piedmont region. These accumulations resulted in collapsed roofs and the closing of some businesses and schools for more than a week. Easterly flow on the south side of a New England high pressure center resulted in unusually strong cold-air damming that forced a shallow layer of cold air at the surface south along the east slopes of the Appalachians, across Georgia and into the Gulf of Mexico. Convective activity over the Gulf of Mexico infused significant moisture into a warm southwesterly airstream in the mid-troposphere that overran the cold air.