This repository provides an updated version of the Morrison et al. (2009) double-moment cloud microphysics scheme. In addition to the Hallett-Mossop mechanism described in the default scheme, this updated version incorporates three additional ice multiplication processes: ice-ice collisional break-up, droplet shattering, and sublimational break-up. The updated "module_mp_morr_two_moment.F" file is designed to replace the default file in the /phys directory of the mesoscale Weather Research and Forecasting (WRF) model, version 4.0.1.