Towards operational lightning prediction in high-resolution versions of the Met Office Unified Model

Lightning has a big impact on human safety, as well as commercial operations, such as oil rigs, wind turbines and the aviation industry. Traditionally, the forecasting of thunderstorms has been done using simple empirical rules generated by forecasters. Of particular interest is ‘helicopter-triggered lightning', a phenomenon which occurs in the North Sea, to the north and east of the UK in winter. This occurs when a helicopter flies close to a charged cumulonimbus cloud, causing lightning to discharge on to, or through the helicopter.

Given recent increases in computing power, we are able to run the operational Met Office Unified Model at high resolution (1.5 km) over the UK, allowing convective features such as thunderstorms to be resolved or partially resolved at the grid scale. In this presentation, we shall examine the progress to date in the ability to predict lightning flash rate in the Met Office Unified model. Taking several relations from recently published literature, we shall examine which relation is performs the best when coupled to the 1.5 km UK model. We shall also examine the ability of the model to predict when clouds will charge, which is important for forecasting the helicopter-triggered lightning phenomenon.