Thunderstorm types and meteorological characteristics of upward lightning

Abstract

Upwardlightning is rare, but destructive and not confined to the winter season as frequently pre-sented in literature. This study identifies the dominant thunderstorm types for upward lightning and the underlying meteorological settings for its initiation in the cold, warm and transition seasons. Further, it assesses the ability to diagnose the upward lightning occurrence at the Gaisberg Tower (Austria) from meteorological conditions using random forest models. Results show that high-shear and high-wind speed thunderstorms with enhanced particle loadings dominate upward light-ning initiation in the cold and in the transition seasons. In the warm season this dominance is reduced due to an increase in high-CAPE thunderstorms associated with increased low-level moisture and higher-based cloud charge centers. The ability to diagnose upward light-ning is highest in winter and when it occurs associated with the dominant wind-field thunderstorm type in combination with enhanced cloud physics.