An operational system using dual-polarimetric radar data to estimate rainfall across the Tennessee Valley, independent of rain gauge input, has been developed for implementation by a regional water management organization, the Tennessee Valley Authority (TVA). This operational system employs the dual-polarimetric Advanced Radar for Meteorological and Operational Research (ARMOR) to provide quantitative rainfall estimation for watersheds across the Tennessee River Valley. The ARMOR rainfall estimates have been compared with measurements from rain gauges across northern Alabama and southern Tennessee. Comparison with the TVA rain gauge network indicates a 6-hr rainfall accumulation bias in sub-basins of only -8% with roughly a 15% random error. Based on previous studies and the relatively low bias and standard errors present in the ARMOR data it is expected that the radar estimates will improve the hydrograph forecasts, but this requires testing in a distributed inflow model to confirm.

Relative to project objectives set forth by TVA, the demonstrated ability to accurately map rainfall with the ARMOR dual-polarimetric radar in the Tennessee Valley should enable the TVA to reduce its reliance on, and costs associated with, coarse rain gauge networks that do not adequately cover individual sub-basins in the watershed.