This research analyses the impact of using surface observations and observations at 70 m above the surface to estimate mixing ratio and potential temperature throughout the summer daytime boundary layer. Soundings were created to represent the actual conditions, and errors were computed when surface values and values at 70 m above the surface were assumed to represent the entire boundary layer. Data for this research was collected during the International H2O Project (IHOP). The datasets of interest came from the University of Wyoming’s King Air aircraft and from surface stations.

Results showed that mixing ratio and potential temperature were rarely constant with height throughout the boundary layer during IHOP. When mixing ratio was assumed equal to the surface value, significant errors could occur in the forecast for severe storm potential as defined by the atmospheric stability indices. Boundary layer estimates of potential temperature and mixing ratio from surface values yielded average overestimates of 1.5 K and 1 g/kg. When applied to a convective sounding, such errors corresponded to significant changes in the convective available potential energy (CAPE) and lifted index (LI). When the boundary layer potential temperature and mixing ratio values were set equal to the values at 70 meters above the surface, the errors in potential temperature and mixing ratio estimates were significantly reduced. The author speculates that if it were better understood how mixing ratio evolved throughout the daytime boundary layer, then there would be increased forecast accuracy for convective precipitation.