An Observation of the Relationship between Supercell Structure and Lightning Ground-Strike Polarity

Michael L. Branick NOAA/NWS Forecast Office, Norman, Oklahoma

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Charles A. Doswell III NOAA/ERL/National Severe Storms Laboratory, Norman, Oklahoma

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Abstract

Cloud-to-ground lightning data are presented from tornadic thunderstorms in Oklahoma, Kansas, and Nebraska on 13 March 1990. The tornadic storms from northern Oklahoma northward into Kansas and Nebraska produced an unusually high percentage of positive cloud-to-ground (+CG) flashes, whereas those in central and southern Oklahoma produced mostly negative flashes. Visual evidence indicates a distinct difference in structure between the northern storms, which produced high +CG rates, and the southern storms, which did not. The storms with high +CG rates possessed characteristics of storms in the low-precipitation (LP) portion of the supercell spectrum. In contrast, visual and radar characteristics indicate that the southern storms with lower +CG frequencies were in the high-precipitation (HP) portion of the supercell spectrum. These findings are consistent with another recent study linking high +CG rates with LP storms. Based on these observations, potential benefits of real-time lightning-strike data to forecast and warning operations are considered.

Abstract

Cloud-to-ground lightning data are presented from tornadic thunderstorms in Oklahoma, Kansas, and Nebraska on 13 March 1990. The tornadic storms from northern Oklahoma northward into Kansas and Nebraska produced an unusually high percentage of positive cloud-to-ground (+CG) flashes, whereas those in central and southern Oklahoma produced mostly negative flashes. Visual evidence indicates a distinct difference in structure between the northern storms, which produced high +CG rates, and the southern storms, which did not. The storms with high +CG rates possessed characteristics of storms in the low-precipitation (LP) portion of the supercell spectrum. In contrast, visual and radar characteristics indicate that the southern storms with lower +CG frequencies were in the high-precipitation (HP) portion of the supercell spectrum. These findings are consistent with another recent study linking high +CG rates with LP storms. Based on these observations, potential benefits of real-time lightning-strike data to forecast and warning operations are considered.

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