The influence of cloud merging on extreme precipitation formation in Saint-Petersburg
A.A. Sin’kevich1, I.A. Tarabukin1, A.B. Kurov1, I.E. Yusupov2, M.L. Toropova1, Yu.P. Mikhailovskii1
1The Voeikov Main Geophysical Observatory, St Petersburg, Russia
2Saint-Petersburg State University, St. Petersburg, Russia
Keywords: thunderstorm, lightning, radar characteristics, cloud merging
Abstract
Characteristics of a convective cloud with heavy rainfall over Saint-Petersburg and Leningrad region on 1st of July, 2023, are considered. The analysis was based on data of the weather radar DMRL-C, weighing precipitation gauges Pluvio2 200, and two lightning detection networks. The appearance and development of Cb under study was a result of merging two convective clouds. During their development the clouds slowly converged moving towards Saint-Petersburg from the southwest. Measurements have shown that the cloud merging led to explosive growth of the cloud top, which reached an altitude of 13.4 km; significant increase in the maximal reflectivity up to 69 dBZ, in volume of the cloud supercooled part with high reflectivity, volumes of the cloud with graupel and hail, precipitation intensity up to 140 mm/h, and lightning rate. The appearance of “the cloud bridge” was recorded. It has been shown that it consisted of graupel and wet snow particles.
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