Improving the parametrization of microphysics for high-resolution NWP forecasts of deep convection, using observations from the UK CSIP campaign

Numerical Weather Prediction (NWP) models with grid resolutions of the order of a kilometre will become operational over the next few years. One of the goals is to be able to predict the life cycle of individual convective storm cells as accurately as possible. The details of the cloud and precipitation microphysical processes that are parametrized in the model play a vital role in the development of deep convective cells in the forecast, yet there are still uncertainties in many aspects of the parametrization and the degree of complexity of the system that needs to be adequately represented.

This paper considers different aspects of the cloud and precipitation microphysics parametrization in the Met Office Unified Model at convective-scale resolution (around 1 km grid resolution). Observations from the Convective Storms Initiation Project (CSIP), an observational campaign over the southern UK in 2005, are used to assess the model performance and suggest improvements to the microphysics parametrization for operational forecasting of deep convection.