Quasi-Linear Convective Systems and Derechos across Europe: Climatology, Accompanying Hazards, and Societal Impacts

In this work, we use 8 years (2014–2021) of Operational Programme for the Exchange of Weather Radar Information (OPERA) radar data, lightning detection network (ATDnet) data, and severe weather reports to create a climatology of quasi-linear convective systems (QLCSs) in Europe. In the first step, 15-min OPERA radar scans were used to identify 1475 QLCS cases. The manual investigation of each individual led to the recognition of QLCS morphological and precipitation archetypes, areal extent, width, length, duration, speed, forward motion, accompanying hazards, injuries, and fatalities. Severe weather reports, lightning data, and morphological properties were used to classify QLCSs according to their intensity into 1151 marginal (78.0%), 272 moderate (18.5%), and 52 derecho (3.5%) events. Spatio-temporal analysis indicate that QLCSs are the most frequent during summer in Central Europe, while in southern part of Europe their occurrence is extended to late autumn. A bow echo morphological archetype occurred in around 29% of QLCS cases, while a mesoscale convective vortex occurred in almost 9%. Among precipitation modes, trailing and embedded stratiform types accounted for around 50% of QLCSs. Based on ESWD Database we found that the most frequent QLCS-related hazard was lightning (taking up on average 94.4% of the area impacted by QLCS), followed by severe wind gusts (7.9%), excessive precipitation (6.1%), large hail (2.9%), and tornadoes (0.5%). Derechos had the largest coverage of severe wind reports (49.8%), while back-building QLCSs were mostly associated with excessive precipitation events (13.5%). QLCSs caused 104 fatalities and 886 injuries. Nearly half of all fatalities and injuries were associated with only the 10 most impactful QLCS events, mostly warm-season derechos producing severe to extreme widespread wind gusts.