19A.7 Storm Environments Supporting Spaceborne Radar and GOES-observed Extreme Convective Storms in Central Argentina

Wednesday, 30 August 2017: 12:00 PM
Vevey (Swissotel Chicago)
Stephen W. Nesbitt, Univ. of Illinois, Urbana, IL; and K. L. Rasmussen, M. Cancelada, P. Salio, L. Vidal, J. Mulholland, and R. J. Trapp

Spaceborne radar evidence, including from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR), indicates that the convection in central Argentina is globally unique in its intense vertical structure, rapid upscale growth, broad horizontal organization, and lightning production. Many mesoscale convective systems (MCSs) propagate over long distances after they are commonly initiated in the foothills of the Andes and Sierras de Córdoba (SDC), a lesser mountain range east of the primary Andes Cordillera. However, isolated convection also forms near and apart from the topography. This convection is known to produce copious hazardous weather in the form of large hail, damaging winds, flash flooding, and tornadoes, with strong regional variability in severe weather types observed between regions close and apart from the Andes.

The unique convective characteristics and storm structures in the region have motivated RELAMPAGO-CACTI (Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations–Cloud, Aerosol, and Complex Terrain Interactions, http://relampago-cacti.org), an international multi-agency field campaign that will occur in austral Spring 2018. In preparation for the field phase, this study investigates convective modes in this region as observed from extreme convective structures identified by the TRMM satellite and infrared satellite data over a period 1998-present. A strong contrast in convective intensities and modes is seen between the regions in the immediate lee of the Andes (near Mendoza, Argentina) and near and east of the SDC (near Córdoba, Argentina). GOES satellite cloud tracking of the life cycle of these storms (identified using a 250 and 235 K threshold) reveals the locations of initiation, maturity, and decay of the TRMM-identified storms. Reanalysis composites during TRMM-GOES observed events along these reveal key differences between these two regions in the spatial configuration of synoptic forcing, thermodynamic properties, bulk shear, and helicity that are spatially related to the observed climatological differences in radar-observed storm structures.

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