Episódio de tempo severo em Brasília-DF: importância de fatores locais no desenvolvimento de convecção profunda.

Abstract

Various environmental factors including geographic location, topography and significant variability in the intensity and direction of the synoptic flow make the central-eastern region of Brazil one of the favorable areas for the development of deep convective activity and severe weather conditions. On the 10th of April 2011, the occurrence of thunderstorms accompanied wind gusts and hail caused inundations in various areas of the Federal District (DF), extensive traffic jams in Brasília, loss of electric power supply and many unrooted trees. The intense rainfall that affected the region inundated part of the University of Brasília building causing irreversible damages. This study evaluates the influence of the local and synoptic scales on this severe weather event by means of the analysis of informations collected at the Brasília International Airport, Juscelino Kubitschek President (SBBR), remote sensing products (GOES 12 satellite images and Gama-DF radar images). Aiming to investigate also the relative importance of the association between atmospheric variables in the evolution of the convective systems and occurrence of extreme rainfall, the factorial analysis by principal components was used. The results show that a model with three components is sufficient for representation of the data structure retaining 88% of the total variance. The convection shows that the region located to the southwest of the DF represents a preferential area for the formation of convective cells with a linear alignment pattern. It was verified also that in spite of the efficiency of the statistical methods used in this study, it was only the use of the radar images that effectively allowed explaining the formation, evolution and displacement of the convective lines (CL).