Improvements in nowcasting capability: analysis of three structurally distinct severe thunderstorms across northern England on 1 July 2015

Abstract

Three severe and very different storms developed across northern England on 1 July 2015 during a short‐lived hot spell. These events are analysed using a mixture of traditional data sources, as well as the improved UK radar capability and the public crowdsourcing of data, which itself could have a powerful role in future nowcasting. The first storm developed during early afternoon from an area of medium‐level instability, resulting in strong straight‐line winds and localised flash flooding in northeast England. The second storm was rooted to the boundary layer and, from analysis of social media reports, produced a 130km swathe of large hail. Subsequent radar analysis showed this storm to have acquired characteristics of a supercell. Despite the loss of daytime heating, further thunderstorms developed across northwest England later in the evening, albeit rooted to a layer above the boundary layer. However, these storms still produced large hail and frequent lightning, with radar analysis showing the development of a rare elevated supercell.