Análise observacional e numérica da supercélula tornádica de 19 de novembro de 2015 em Marechal Cândido Rondon, Paraná

Abstract

In the mid-afternoon of 19 November 2015, a large multiple-vortex tornado struck the city of Marechal Cândido Rondon, situated in southern Brazil. The tornado-producing left-moving supercell evolved within the range of a dual-polarization S-band Doppler radar that allowing the documentation polarimetric signatures during the tornadic stage. The polarimetric signatures identified an analizes in this study include the ZDR arc, the KDP foot, ZDR and KDP columns, ZDR and hv rings, and the tornadic debris signature, in addition to other more traditional radar signatures like the hook echo, inflow notch, cyclonic velocity couplet, and bounded weak echo region. The general synoptic- and mesoscale atmospheric conditions in which the severe storm developed displayed a very moist subtropical environment with high CAPE, low LCL, and intense mid- and low-level wind shear, but under weak synoptic forcing. As shown in previous studies, this synoptic–mesoscale configuration describes a typical environment for tornadic supercells in southern and southeastern Brazil. In a second part of this work, reflectivity and radial velocity were assimilated in a semi-idealized manner using the CM1 model and the LETKF filter. As ensemble of 50 members was generated with grid spacing of 1km, where the supercellular mode was the dominant convective mode. Most of the simulated supercells displayed morphological characteristics observed in radar data, such as the hook echo and the inflow notch. In their mature phase, the most intense storms had vertical velocities around 7 and 8 ms-1 at low levels and exceeded 30 ms-1 at mid levels. The simulated supercells were able to produce a low-level mesocyclone, although not always very intense. Additionally, the results suggest that there was a tendency to produce high precipitation storms, in contrast to what was observed during the MCR event, where heavy precipitation was not reported.