Utilizing Four Dimensional Lightning Data and Dual-Polarization Radar to Develop Lightning Forecast Guidance

Lightning initiation from airmass thunderstorms is a major forecast challenge faced by the Air Force's 45th Weather Squadron (45 WS), which provides weather support to Cape Canaveral Air Force Station and Kennedy Space Center (KSC). Prior studies have shown that dual-polarization (DP) radar can be used to identify the presence of hydrometeors indicative of cloud charging, leading to improved lightning initiation forecasts. The 45 WS currently uses empirical lightning initiation forecast rules which state that in-cloud lightning is likely within 10 to 20 minutes after radar reflectivity exceeds 37 dBZ above the -10°C level. Rules also exist for cloud-to-ground, anvil, and debris cloud lightning. This study examined over 200 lightning-producing and non-lightning convective cells in order to expand the existing empirical forecast principles to incorporate DP parameters. In-cloud lightning flash data were obtained from the KSC Four Dimensional Lightning Surveillance System (4DLSS). DP radar data were obtained from the Melbourne, Florida WSR-88D. In-cloud lightning initiation forecast lead times, probability of detection, and false alarm rates were compared for a number of candidate DP-based forecast techniques and the current techniques employed by 45 WS.