Cloud and Precipitation Parameterization in a Meso-Gamma-Scale Operational Weather Prediction Model

The paper assesses the difficulties of running an operational NWP model in the resolution range of 3-8 km. In this case, deep convection cells are neither much smaller than the grid box as assumed by most parameterization schemes, nor completely resolved as would be required for them to be treated explicitly. A specific approach is proposed, with an integrated sequential treatment of resolved condensation, deep convection, and microphysics together with the use of prognostic variables. It currently allows for the production of consistent and realistic results at resolutions ranging from a few tens of kilometers down to less than 4 km. Model skill scores and an example of an operational forecast at different resolutions are presented.