Intensification of single cell storms prior to lightning onset

Courtier, B. M., Stein, T. H. M. ORCID: https://orcid.org/0000-0002-9215-5397, Harrison, R. G. ORCID: https://orcid.org/0000-0003-0693-347X, Hanley, K. E. and Wilkinson, J. M. (2019) Intensification of single cell storms prior to lightning onset. Atmospheric Science Letters, 20 (4). e873. ISSN 1530-261X doi: 10.1002/asl.873

Abstract/Summary

Single cell storms in the UK can produce lightning, despite apparently only having developed to towering cumulus rather than cumulonimbus. Such marginal thunderstorms still present severe weather hazards but are difficult to identify and predict and therefore provide a warning. Observations from the Met Office radar mosaic and ATDNet (Arrival Time Difference Network) show that these single cell storms demonstrate a characteristic increase in the area of high reflectivity storm core during the 15 minutes prior to the first lightning. By using the Met Office Unified Model to investigate reflectivity development in modelled storms, a microphysical explanation for the observed reflectivity increase is identified. During a rapid reflectivity increase, the updraft area at the melting layer, the peak updraft velocity and the storm graupel mass increase. The three quantities examined are linked to each other and to the generation of charge within the storm. The production of graupel is promoted by the increase in updraft area and charge separation is enhanced by the faster peak updraft velocity. This explains some of the physical differences between single cell storms that produce lightning and apparently similar storm systems which do not. It also provides a new basis with which to predict lightning hazard for marginal storms.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/81227
Identification Number/DOI	10.1002/asl.873
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Wiley
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