The South American Low-Level Jet Evolution in Two Episodes of Mesoscale Convective Systems

The South American low-level jet (SALLJ), located on the eastern Andes, is responsible for the significant transport of moisture and control of the spatiotemporal distribution of precipitation in South America. The SALLJ is present year-round, but it has a distinct role in the formation of mesoscale convective systems (MCS). This study investigated an unusually intense SALLJ event that occurred in December 2016, which was associated with the formation of two MCS episodes. This analysis used the European Centre for Medium Range Weather Forecasts Reanalysis (ERA5) for the synoptic overview, as well as Integrated Multi-satellitE Retrievals for GPM (IMERG) and infrared brightness temperature data to identify and track MCS precipitation. The NCAR SAAG Weather Research and Forecasting (WRF) simulations were used to examine the MCS vertical structure. Under SALLJ conditions, moist and unstable air, and vertical motions favor the development of deep convection over central and northern Argentina.