321148 Diagnosing Supercell-Boundary Interactions with Polarimetric and Lightning Data

Monday, 28 August 2017
Zurich DEFG (Swissotel Chicago)
Sabrina Jauernic, University of Nebraska, Lincoln, NE; and M. S. Van Den Broeke

Ambient moisture and relative vorticity may be enhanced in narrow zones along surface air mass boundaries. Supercells entering these zones may change intensity and behavior as they cross or move parallel to the boundary and interact with a new environment. Boundary interacting supercells have been the focus of prior studies, however little research has investigated storm response through temporally collocated polarimetric and lightning data. Using these data in conjunction with proximity soundings could improve understanding of this phenomenon. A small sample of supercells moving parallel to different boundary types will be presented. Updraft characteristics such as height and areal extent will be inferred during boundary interactions through investigation of ZDR columns. Interrogation of ZDR arcs in the forward flank will allow inference of changes in low level inflow strength and storm relative helicity. Lightning characteristics such as dominant polarity reversals and lightning jumps will be assessed during boundary interactions. Changes in hydrometeor characteristics inferred though both lightning and polarimetric data in the forward and rear flank downdrafts may give insight into evolution of storm thermodynamics during and after boundary interaction. The outcomes of a boundary interaction may include tornadogenesis, strengthening without tornadogenesis, maintenance of strength, and weakening. A goal of this research will be to preliminarily investigate the feasibility of accurately predicting boundary-interaction outcomes.
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