What is already known:
What this study adds:
The planetary boundary layer (PBL) is often under sampled by current operational atmospheric observation methods, especially during the early evening transition (EET). Other methodology such as specialized equipment at the Collaborative Lower Atmospheric Mobile Profiling System (CLAMPS) or dual-polarization NEXRAD radar could provide more consistent PBL measurements. Often, CLAMPS and the radar do not agree on the height of the PBL during the EET. During the EET the radar indication is often much higher than that of CLAMPS’s estimates. CLAMPS is better suited to detect the low SBL than the radar as it can use not only kinetic data but also thermodynamic data. The radar searches for areas of high Bragg scatter, which show up as near-zero ZDR to indicate the PBL height. We hypothesize that during the EET, the residual layer’s decaying mixing likely dominates any potential ZDR depression signal from the newly forming stable boundary layer—if that stable boundary layer is deep enough for the radar beam to reach it. This study used weather-sensing uncrewed aerial systems (WxUAS) to investigate the character of the layers that these two methods were detecting. These WxUAS data were compared to PBL measurement data collected near Norman Oklahoma on 27 August 2020. With its high-resolution thermodynamic profile measurements, the WxUAS was able to verify that CLAMPS was detecting the SBL, while the radar was seeing an elevated distinctly different layer of the atmosphere. These data were unable to confirm if this layer was a residual layer due to complex structure and lack of continued observation. While this distinct layer may or may not be the residual CBL, it helped contextualize the radar’s indications during the EET providing more understanding of the radar-based method’s capabilities.