Using the Lightning Imager for nowcasting severe convective storms: experience from ESSL-EUMETSAT Testbeds and workshops

ESSL and EUMETSAT have organised several expert workshops on using and visualizing the Lightning Imager (LI) data from the Meteosat Third Generation satellite. Also based on the recommendations gained from the workshop, ESSL developed the LI product visualizations presented to the forecasters at the ESSL-EUMETSAT forecaster training Testbeds in 2024 and 2025. These involved point- and grid-based data, such as the size of observed flashes, group density calculated over small grids, or the spatial extent of the observed flashes. Participants of each of the Testbed weeks were asked to evaluate the products and fill out questionnaires. We present the workshops' main results and the summary of the evaluation provided by the Testbed participants. We concentrate on two issues: how useful the LI data is for nowcasting severe convective storms and which products or visualizations were preferred by the forecasters.Besides that, the ESSL staff has been inspecting the LI data over both convective seasons. Using the experience from 2024, ESSL has produced a guide on using the LI data alongside a detailed description of the LI behaviour for 12 cases of severe and non-severe convective storms. Patterns in LI data were compared with storm hazards on the ground reported in the ESWD. We present some insights gained from the data usage during these two years. This includes some interesting patterns or artifacts, such as a few cases of severe storms showing a sudden dip in the lightning, the occurrence of a lightning ring surrounding the updraft area, or a large fraction of flashes detected from the side of the storm as a reflection from the low clouds.