Shallow cumuli are fair-weather clouds with tops no more than several kilometers above ground. They modulate fluxes of heat and moisture from the ground and cast high-frequency intermittent shadows on photovoltaic (PV) panels. Like deep-cumulus parameterizations, shallow-cumulus parameteriza – tions use a mass-flux method or moist convective adjustment. A difficulty in shallow-cumulus parameterization is interfacing it with other parameteriza- tions. This hinders the simulation of transitions from (overcast) stratocumulus to (broken) cumulus fields (Park & Bretherton 2009) and the simulation of transition from shallow to deep cumulus. ECMWF, GFS, and RAP treat small cumulus clouds using a mass-flux parameterization that is closely related to their respective deep-cumulus parameterizations. NAM uses a moist – adjustment methodology.