The morning transition is the period when the planetary boundary layer (PBL) transitions from stable to unstable conditions. It is critical that numerical weather prediction (NWP) models sufficiently represent the various forcings that contribute to the PBL heat and moisture budgets during the morning transition, as they impact forecasts of air quality, aerosol dispersion, and daytime cloud cover and precipitation. This study assesses the representation of processes that contribute to PBL evolution during the morning transition in NWP model physics parameterizations by applying a mixing diagram framework to observations from the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site and output from the Common Community Physics Package single-column model (CCPP SCM) utilizing the High-Resolution Rapid Refresh (HRRR) physics suite. Although the evolution of mean PBL potential temperature and specific humidity in the SCM is comparable to observations, PBL growth is substantially delayed in time and growth occurs over a shorter time period in the SCM. This delay is partly due to an initially slower rate of surface heating in response to incoming solar radiation and larger ground heat flux in the SCM relative to observations. Replacing the land surface model with prescribed surface fluxes from observations can reduce, but not completely remove, the delay in PBL growth, suggesting that the PBL physics scheme is also a contributing factor to the transition timing and duration. The results of this study highlight the utility of mixing diagrams and SCMs for assessing and improving the representation of transitions within NWP models.