Severe Convective Storms across Europe and the United States. Part I: Climatology of Lightning, Large Hail, Severe Wind, and Tornadoes

Abstract

As lightning-detection records lengthen and the efficiency of severe weather reporting increases, more accurate climatologies of convective hazards can be constructed. In this study we aggregate flashes from the NLDN and ATDnet lightning-detection networks with severe weather reports from ESWD and SPC Storm Data on a common grid of 0.25° and 1-hour steps. Each year approximately 75–200 thunderstorm hours occur over the southwestern, central and eastern United States, with a peak over Florida (200–250 hours). The activity over the majority of Europe ranges 15–100 hours, with peaks over Italy and mountains (Pyrenees, Alps, Carpathians, Dinaric Alps; 100–150 hours). The highest convective activity over continental Europe occurs during summer and over the Mediterranean during autumn. The United States peak for tornadoes and large hail reports is in spring, preceding the maximum of lightning and severe wind reports by 1–2 months. Convective hazards occur typically in the late afternoon, with the exception of the Midwest and Great Plains, where mesoscale convective systems shift peak lightning threat to the night. The severe wind threat is delayed by 1–2 hours compared to hail and tornadoes. The fraction of nocturnal lightning over land ranges 15%–30% with lowest values observed over Florida and mountains (∼10%). Wintertime lightning shares the highest fraction of severe weather. Compared to Europe, extreme events are considerably more frequent over the United States, with maximum activity over the Great Plains. However, the threat over Europe should not be underestimated, as severe weather outbreaks with damaging winds, very large hail and significant tornadoes occasionally occur over densely populated areas.

Reconstruction of Violent Tornado Environments in Europe: High‐Resolution Dynamical Downscaling of ERA5

“…Interest in tornado research has significantly increased in the 21st century, but due to the lack of tornado reporting practices in many European countries, the tornado threat is still likely underestimated (Antonescu et al., 2017, 2018; Pîrloagă et al., 2021). Much higher efficiency in tornado reporting can be observed across highly populated Western and Central Europe (Groenemeijer et al., 2017; Taszarek, Allen, Groenemeijer, et al., 2020), where severe weather outbreaks often produce large societal impacts and considerable damage to infrastructure (Doswell, 2003; Grieser & Terenzi, 2016; Púčik et al., 2019).…”

A gridded 30‐year days of thunder climatology for the United Kingdom

“…The Met Office currently has a digital archive of LLN locations from 1990 until the present. To avoid the difficulty of varying networks, other climatologies have either been limited to 13 or fewer years (Anderson and Klugmann, 2014; Rädler et al ., 2018; Enno et al ., 2020; Taszarek et al ., 2020) or have tried limiting their analysis to only the largest strikes (e.g., flashes with a peak current lower than 15 kA as measured by the LLN were removed), assuming that these are the most likely to be detected (Taszarek et al ., 2021). Other methods using only surface stations have also been published (Perry and Hollis, 2005); these are limited, as the density of both the staffed observing network and volunteer observing network has reduced significantly in recent years, therefore reducing the places reporting audible thunder.…”

Amplification of Annual and Diurnal Cycles of Alpine Lightning

“…We aim to investigate the historic evolution of lightning across the European Eastern Alps. Climatologies show that this region is a hot spot within Europe (Enno et al, 2020;Taszarek et al, 2020). The interactions of the complex terrains and atmospheric processes such as circulation and radiation lead to persistent forcings (Bertram and Mayr, 2004).…”