Warnings of Intense Convective Rainfall in the UK

Oral presentation

Flooding is a major and increasing hazard in the UK. While much attention is focused on the widespread floods associated with winter storms, rapid flooding due to intense summer convection is an increasing threat. Whereas Numerical Weather Prediction provides valuable guidance in the prediction of winter storms, summer convection is generally only predicted at low confidence over large areas, and warnings are currently issued accordingly at the lowest level of confidence. While these warnings have some value for emergency managers, they are of little use to the general public, as most of the area of the warning will be unaffected. However, for a minority of the most extreme events, such storms pose a significant threat to life. My presentation will describe an approach to formulating a warning system for such storms using the end-to-end value chain approach promoted by the WMO/WWRP HIWeather project. I shall start by identifying the key vulnerable communities and their possible responses. I shall then look at how this information could be produced, at what lead time, and the challenges of delivering it to those likely to be affected. I shall assess the credibility of the approach for the intense rainfall events of summer 2023 and draw some conclusions about further developments required to enable such a warning system to be implemented.