OVER THE COMPLEX TERRAIN OF

This study examines the similarities and differences between five events when supercells over the eastern Tennessee River Valley had either low or high tornado-producing efficiency. The three events with a high tornado-producing efficiency (defined in this study as an event where every supercell produced at least one tornado) were characterized by the tornado-producing supercells tracking near a well-defined, preexisting west-to-east oriented quasi-stationary frontal boundary. The other two events with a low tornado-producing efficiency had supercells that were located and moved farther away from a south-to-north oriented cold front. In the high tornado-producing efficiency events, the supercells likely encountered lower lifted condensation level (LCL) heights and higher helicity values for a longer distance along the west-to-east oriented quasi-stationary frontal boundaries. In the low tornado-producing efficiency events, the supercells encountered higher LCL heights and lower helicity values as they propagated farther away from the south-to-north oriented cold fronts, especially across the Great Tennessee Valley where the lowering elevation from the Cumberland Plateau aided in the higher LCL heights. During the one non-tornado-producing event, the combination of high LCL heights, a lack of low-level directional wind shear, and the location of the supercell paths away fro