During the International H2O Project (IHOP) field mission conducted over the Southern Great Plains during May-June 2002, a large array of state-of-the-art ground-based and airborne remote and in situ sensors provided extensive measurements of water vapor in order to better understand the influence of water vapor variability on the initiation of deep convection and to improve the quantification and prediction of precipitation associated with these storms. These sensors included the NASA Langley Lidar Atmospheric Sensing Experiment (LASE) airborne DIAL system, which was deployed from the NASA DC-8 aircraft, as well as numerous dropsondes deployed from the DLR Falcon and Lear aircraft, and radiosondes launched by NCAR and the DOE ARM program at several sites. LASE provided water vapor, aerosol, and cloud profiles along the flight track of the NASA DC-8, which was nominally flown at an altitude of 7.3 km (24 kft). Total precipitable water vapor measurements derived using the Terra MODIS near infrared technique were evaluated using the LASE measurements and combined with the water vapor profiles measured by the various airborne and ground-based in situ and remote sensing techniques to develop 3-D visualizations of water vapor distributions over the Southern Great Plains. These water vapor profiles are used together with temperature profiles from radiosondes, dropsondes, and the Scanning High-resolution Interferometer Sounder (SHIS) to derive distributions of relative humidity, equivalent potential temperature, and stability indices in order to help understand the role of water vapor on convective initiation. Profiles of aerosol scattering ratio, which were also measured by LASE, are used in conjunction with Terra MODIS retrievals of aerosol optical thickness to develop 3-D visualizations of aerosols over the Southern Great Plains. These visualizations show the presence of smoke from forest fires in New Mexico and Colorado. The combination of these various measurements provides a unique dataset for studying convective initiation.