Origins of positive cloud-to-ground lightning flashes in the stratiform

7 [1] The origins of positive cloud-to-ground (+CG) 8 lightning in the stratiform region of a leading-line, 9 trailing-stratiform mesoscale convective system (MCS) are 10 investigated. Platforms include radars, NLDN data, and a 11 VHF 3-D lightning mapping system. This study examines a 12 small asymmetric MCS that occurred near the Colorado13 Kansas border in June 2000. In this storm 39 of the 269 14 +CGs produced over a nearly 5-hour period came to ground 15 within the stratiform region. Of these, 30 initiated in the 16 leading convective line and propagated rearward before 17 coming to ground. Nine other +CGs originated within the 18 stratiform region. Stratiform +CGs were observed to 19 propagate mostly horizontally through vertically thin 20 layers. The observations suggest that stratiform charge is a 21 conduit for +CG lightning from the convective line, and can 22 initiate +CGs as well.