Characterization of Storm Types During a 30-HOUR Period of Radar Observations During the Dry-to-Wet Atmospheric Mesoscale Campaign of the LBA in 2002
Gerhard
Held, Instituto de Pesquisas Meteorológicas, Universidade Estadual Paulista, BAURU, S.P., Brazil, Gerhard@ipmet.unesp.br
(Presenting)
The observations described in this paper were made with an S-band Doppler radar, which was located about 40 km south of Ouro Preto do Oeste (Rondônia).
A very interesting situation occurred in the morning of 07 October 2002, when a storm developed from its “First Echo” (FE; operationally displayed reflectivity ³ 20 dBZ beyond 25 km range due to the application of a “Doppler Filter 3”) up to 20 km height within less than 30 min, about 140 km west-north-west of the radar. Its echo core (and presumably its updraft) was upright, as of the vast majority of storms, which I observed during the period 6-21 October 2002. However, almost simultaneously, about 80 km to the east, another multicellular storm developed, but the two main cores were strongly tilted. This storm only reached 13 km in height, but was longer lasting than the one with the vertical cores. Radial velocities did not show any significant differences. Later during this day, these two complexes and other isolated to scattered, smaller storms, created a huge stratiform cloud cover, which resulted in occasional isolated showers and aided the development of new cells under its umbrella.
In the evening of the same day (± 20:00 LT), a strong Microburst was observed over the urban area of Ji Paraná. During the early hours of the following morning (± 02:30 LT) very isolated cells developed at random over the eastern part of Mato Grosso, consolidated after about one hour, forming a Mesoscale Convective System (MCS), which ultimately moved at 50-60 km.h-1 across the whole State of Rondônia. The leading edge was characterized by very strong and tall cells, with a steep gradient of reflectivity, trailing behind a large area of stratiform precipitation.