Derecho and derecho-like events in northern Eurasian forests

Derechos and derecho-like storms are severe, long-lived convective wind events that regularly cause fatalities and widespread damage, including large-scale forest loss. This study presents the first dataset on derecho-like storms that have occurred in the Russian forest zone in the 21st century, and considers their main climatic characteristics and formation environments.

By combining ground-based and satellite observations, particularly satellite-derived data on windthrow events, we identified 41 derecho-like storms, 31 of which occurred in European Russia. Based on their path length and storm intensity indicators, we classified five events as derechos, including two previously confirmed derecho events that occurred in the summer of 2010 and one derecho event that was first confirmed in Siberia. The frequency of derecho-like events in the Russian forest zone is three to four times lower than that of warm-season derechos in Central and Western Europe. The highest frequency (one case every four to five years) is found in the Middle Volga region. The highest number of events occurred in June and July in 2010 and 2020. Despite their low frequency, derecho-like storms cause substantial damage; for example, 91 fatalities and 539 injuries have been associated with the 41 storms considered. However, data on economic losses is incomplete. Derecho-like storms are responsible for the loss of forests in an area totalling 2,705 km², which constitutes 41.7% of the total windthrow area in Russia between 2001 and 2024, and 52.4% of that in the forest zone of European Russia.

According to satellite observations, the majority of these storms in the Russian forest zone are produced by quasi-linear convective systems or mesoscale convective complexes of meso-α scale. Progressive and hybrid events dominate the sample, which is typical of the warm season. According to the ERA5 reanalysis data, the convective environments of derecho-like events are similar to those associated with severe convective windstorms in the U.S. and Europe during the warm season. For example, most events form under conditions of high CAPE and high shear. However, the most severe storms, classified as derechos, do not correspond to the highest values of convective variables. 

The study was supported by the Russian Science Foundation (grant no 24-17-00357).