The HAWC (High-altitude, Aerosols, Water vapour, and Clouds) mission is a satellite project being developed by the Canadian Space Agency. HAWC will consist of three satellite instruments, including the SHOW (Spatial Heterodyne Observations of Water) instrument that will take H2O measurements in the upper troposphere lower stratosphere (UTLS). Once SHOW launches, comparison studies will be done with ground based instruments, and airborne observation campaigns to assess the quality of the data being collected. These comparison studies must be informed by a knowledge of the variability of the gas of interest in order to determine how close measurements must be to be considered coincident. This project aims to investigate the natural variability of H2O in the UTLS, to understand how it will contribute to comparisons between SHOW and other measurements. This work is done using an orbit simulator for the HAWC mission and modeled water vapour concentrations. The initial results from the work will be presented, alongside plans for improving the methodology.