ground portion of the atmosphere using GIS technology. The potential for complete and partial radar beam blockage can be evaluated in the context of hydrologic basins for which coverage is sought. Basin size, average slope, orientation with respect to the movement of dominant weather patterns, characteristics of soil, land cover and land use, and channel hydraulic aspects determine the amount of rain that is likely to cause flash flooding and where it may occur. These characteristics, together with local hazard vulnerabilities, can help determine priorities of site selection.