Sensitivity of convective initiations to soil moisture and directional shear in k-scale models

Convective storms impact populations all over the world, bringing heavy rainfall, strong winds, lightning and sometimes hail. These hazards can lead to flooding, wildfires, damage to infrastructure and loss of life.  Improved forecasting of storms hazards requires accurate prediction of the location and timing of convective initiation. Understanding factors that influence where convection kicks off is therefore crucial for reducing the impact of thunderstorms on the population.

Mesoscale soil moisture heterogeneity can trigger sea breeze like circulations that favour convective initiation over dry soil patches. Recent observational work over Sub-Saharan Africa has revealed that the sensitivity of convective initiation to soil moisture is enhanced by wind shear, with the most rapidly developing storms occurring when the mid-level wind direction opposes low-level soil moisture induced circulations.

The current work evaluates the representation of the observed interaction between soil moisture, wind shear and convective initiation in current kilometre-scale models, including DYAMOND-3 year-long global UM simulations. We further exploit RAL3 simulations to further our understanding of the observed mechanism and explore the impact of different wind shear configurations on convective updrafts and moisture inflow.