Convective-Scale Practical Predictability Within Different Convective Regimes

Flooding from intense rainfall is driven primarily by convective rainfall. However, advances are still being made in understanding the predictability of these events; especially as they can occur within different convective regimes. Two surface-water flooding cases, one quasi-equilibrium event and one non-equilibrium event, within the United Kingdom, are examined within the operational, convection-permitting, Met Office Global and Region Ensemble Prediction System for the United Kingdom (MOGREPS-UK). The perturbation growth is examined, and then considered further with a super ensemble. This super ensemble is constructed with a physically-based stochastic boundary-layer scheme, currently being developed at the Met Office, to determine the impact of perturbing convection-permitting ensembles at different scales. Perturbing at different scales will enable the scales that have stronger influences in the different regimes to be determined in a practical predictability experiment. Identifying the dominant perturbation growth scales within different regimes could help enhance the forecasts of flooding form intense rainfall events and would then result in improved warnings for these events.