Geographic factors strongly influence the atmospheric processes that lead to heavy rains. This doctoral dissertation project will provide an analysis of the subsynoptic character of heavy rain for a broad area encompassing the flood-prone Appalachian mountains of the United States. The horizontal movement of masses of air that causes changes in the physical properties of air will be calculated for a large, spatially unbiased sample of heavy rain events. A principal components analysis will be performed to identify modes of covariance in the advection fields associated by these air movements. This analysis will be followed by a cluster analysis to objectively determine groups of heavy rain events with common low-level moisture, thermal and mid- level vorticity advection patterns. After examining geographic patterns in the occurrence of heavy rain groups, subsynoptic scenarios of heavy rain for the Appalachian region will be developed. This project will provide a better understanding of the role of advection processes in heavy rain development. Patterns of geographic variations expected in the relationship of the advection fields will permit inferences to be made about the ways that mountain orientation and the location of moisture sources alters the subsynoptic regimes associated with heavy rainfall. The development of heavy rain scenarios for the flood-prone Appalachian region will provide forecasters with much needed guidance in the prediction of heavy rain. This project also will provide an excellent opportunity for a promising young scholar to continue to develop independent research skills.
