Correspondence between MTG-LI satellite-based lightning detections and severe weather reports across Europe

We investigated the link between satellite-based lightning detection and severe weather occurrences, focusing on the hypothesis that severe thunderstorms with strong updrafts would produce a high quantity of relatively small lightning flashes. This study utilizes data from the Meteosat Third Generation Lightning Imager (MTG-LI) and ground reports from the European Severe Weather Database (ESWD), encompassing 22.7 million lightning flashes and 26,000 severe weather reports from July 2024 to May 2025.

While over half of all severe weather events were not accompanied by ‘small’ lightning flashes, size boundary defined by the 25^th percentile of the lightning size distribution of the data, a distinct subset of events, particularly large hail, exhibited an exceptionally high concentration, with some instances exceeding 1900 small flashes within the 45- minute window and 20km radius. Specifically, 19.7% of all severe weather events, with and without lightning, were associated with a ‘high’ density of small flashes, a threshold determined by the 75th percentile of the distribution of a density grid specifically designed for this research. Results showed that hail events are notably more correlated with a higher concentration of small lightning flashes compared to other severe weather types, with this correlation increasing significantly with hail size, reaching up to 83.3% for hail over 8cm.  We will report on our efforts to geographically and statistically distinguish regions less prone to reporting, aiming to improve the reliability of hotspot-to-event correlations. This study highlights the potential of MTG-LI data as a valuable indicator for nowcasting severe weather, especially for large hail events.