We evaluate a similarity-based optical turbulence model that estimates diurnal values for Cn2 from easily obtained local terrain and environmental information by comparing it with scintillometer data taken at the Army Research Laboratory"s A_LOT facility in Adelphi, Maryland. The A_LOT facility is characteristic of many planned urban sites for free-space laser communication. One end of the test site is on top of a two-story building, and the other end is a water tower about 70 meters high. This comparison examines the effects of the asymmetric location, such as the non-uniform height above ground and surface roughness length. We found that by emphasizing the terrain type directly in front of the receiver and assuming the height above ground to be the height of the receiver, model results compare favorably with experimental data.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.