CONVECTIVE AND NON-CONVECTIVE GENESIS IN MAXIMUM WIND GUSTS ASSOCIATED WITH EXPLOSIVE CYCLOGENESIS IN SOUTHERN BRAZIL: THE JUNE/JULY 2020 EPISODE

Abstract

On June 30 and July 1, 2020, the southern region of Brazil was the scene of an explosive cyclogenesis that directly impacted society, causing, material, economic and social damage and human fatalities. In the present article, the genesis of the absolute maximum gusts (≥20 m/s) occurred during that extreme meteorological event is characterized. From the methodological application it was possible to differentiate two main groups with different gusts: one of convective origin and the other, non-convective. In addition to the different genesis, the geographic coverage and the period in which the absolute maximum gusts occurred in each group, attest that although affected by the extratropical cyclone, the relative position to it was preponderant. A cold front system caused a squall line that was responsible for the absolute maximum gusts belonging to the first group, which, given the wide-ranging conditions (from the southern portion of the Paraná State to the north of the Rio Grande do Sul), could be treated by using the meteorological term derecho. In the second group, that is, non-convective gusts, the intense pressure gradient given by the deepening of the extratropical (explosive) cyclone over the ocean, conditioned absolute maximum gusts in the coastal strip, especially in Rio Grande do Sul State.