The Predictability of the Southern England 23 October 2022 Severe Downbursts

Accurate prediction of damaging straight‐line wind events from convective storms relies heavily on storm morphology and nowcasting. Utilising the Microburst Wind Potential Index in ensemble forecasts we examine the predictability of its different components for a damaging quasi‐linear convective system (QLCS) on 23 October 2022 to determine their importance in quantifying downburst speed. Four regional model configurations of the Unified Model are used to show that the uncertainty in downburst speed equates to approximately 5 kn of spread in 13 h. This spread is dominated by uncertainty in the low‐level vertical humidity gradient. The determination of the main source of spread provides valuable information to forecasters and consideration across multiple cases could lead to increased understanding of where the uncertainty in downbursts is derived from and thus improve warnings.