Characteristics of cloud-to-ground lightning in severe and nonsevere storms over the central United States from 1989-1998

Over a region from the Kansas/Colorado border to Minnesota, previously associated with positive anomalies in the mean annual positive cloud-to-ground (CG) lightning percentage and positive peak current, we describe significant differences in the properties of CG lightning flashes between warm-season severe (i.e., large hail or tornado producing) and nonsevere storms. The percentage of CG lightning flashes lowering positive charge to ground was substantially higher in severe storms (i.e., up to three times higher). The median positive peak current in severe storms was significantly larger (i.e., by about 25%). Finally, the median negative peak current in severe storms was very low (i.e., as low as 12-16 kA) and was noticeably smaller than in nonsevere storms (i.e., by at least 10%). Severe storms appeared to be significant producers of positive CG lightning in the anomaly region (AR). Up to 30%-70% of warm season positive flashes in the AR were associated with severe storms. Only 2%-30% of negative flashes were associated with severe storms in the AR. As a result, the mean warm season (and likely annual) positive anomalies in positive CG percentage and peak current are likely associated with a unique class of severe, organized storms that occur preferentially in this geographical region. We found substantial differences in the properties of CG lightning flashes associated with severe storms in other regions. For example, the mean warm season properties of CG lightning associated with severe storms in the region of peak large hail and tornado activity (e.g., Oklahoma) were fundamentally different (i.e., significantly lower positive CG percentage, lower positive peak currents and higher negative peak currents) compared to severe storms over the AR from western Kansas to Minnesota.