Variations in Cloud-to-Ground Lightning Characteristics among Three Adjacent Tornadic Supercell Storms over the Tennessee Valley Region

摘要

The contrasting behavior of cloud-to-ground (CG) lightning associated with three adjacent supercell thunderstorms observed on 18 May 1995 is examined. Thunderstorm characteristics and anvil interactions are related to north-south variations in CG lightning properties. While tornadic activity was not consistently related to variations in CG properties, radar reflectivity factor area greater than 65 dBZ was generally inversely related to CG frequency. It is hypothesized that suppression of CG activity was produced by reduction of large number concentrations of precipitation-sized particles (i.e., presence of large hail) in the particle interaction mixed phase region. It is further hypothesized that seeding from upstream storm anvil ice was associated with nearly coincident enhancement of CG activity in downstream storms. Likewise, it is hypothesized that the reduction in 65 dBZ echo area (inferred suppression of hail) is related to this inferred anvil seeding process.