Evolving dominant charge structures in west Texas on 4 June 2012

On 4 June 2012 isolated storms initiated within range of the West Texas Lightning Mapping Array (LMA) and grew upscale into a mesoscale convective system (MCS). Part of the MCS remained over the West Texas LMA and Southwest Oklahoma LMA domains until it dissipated overnight. Initial storm cells developed within a relatively dry mid-level environment and were observed to contain a mid-level positive charge and predominantly negative intracloud (-IC) flashes. Only storms with this charge structure were observed for the first 40 minutes of convection. However, later storm cells and multicellular clusters, both further east in deeper moisture and within areas that had previously been moistened by convection, were primarily observed to contain a mid-level negative charge and +ICs at upper levels in each cell. Both -IC and +IC dominated storm cells were observed simultaneously for at least 90 minutes during this transition. As this case involves many storm cells of differing charge structures over a relatively long period, it will be used to examine the utility of existing models of electrification and microphysics processes in predicting the influence of environmental controls, including temperature and moisture, on the resulting charge structure.