Winter Weather Forecasting throughout the Eastern United States. Part III: The Effects of Topography and the Variability of Winter Weather in the Carolinas and Virginia

Abstract

Winter weather in the Carolinas and Virginia is highly variable and influenced by the area's diverse topography and geography. The Gulf Stream, the highest mountains in the Appalachians, the largest coastal lagoonal system in the United States, and the region's southern latitude combine to produce an array of weather events, particularly during the winter season, that pose substantial challenges to forecasters. The influence of the region's topography upon the evolution of winter weather systems, such as cold-air damming and frontogenesis, is discussed. Conceptual models and specific case studies are examined to illustrate the region's vast assortment of winter weather hazards including prolonged heavy sleet, heavy snow, strong convection, and coastal flooding. The weather associated with these topographic and meteorological features is often difficult for operational dynamical models to resolve. Forecasting precipitation type within the region can be especially difficult. An objective technique to forecast wintry precipitation across North Carolina is presented to illustrate a 1ocally developed forecast tool used operationally to supplement the centrally produced numerical guidance. The development of other forecast tools is being pursued through collaborative studies between the National Weather Service Forecast Office in Raleigh?Durham, North Carolina, and the Department of Marine, Earth and Atmospheric Sciences at North Carolina State University.