Above the melting level, enhanced Zdr and Kdp, and a drop in ρhv at the cellular / updraft scale preceded the initial lightning flash in the storm. The first six flashes were negative cloud to ground flashes. The polarimetric signature in question is associated with lofted raindrops which serve as nuclei for riming graupel upon glaciation (Bringi et al. 1997, Jameson et al. 1996). The signature was absent in nearby cells, which did not produce lightning. The polarimetric data are discussed in the context of charge geometry within the storm as inferred from each flash within the storm and from vector electric field data.