As a microcomputer program with modest data requirements, the Snowmelt Runoff Model (SRM) has been successfully applied to simulate and forecast runoff from seasonally snow-covered basins around the world. The existing SRM uses the Temperature Index method, a single-index equation based on daily temperature, to predict snowmelt runoff. Recent work to enhance SRM has added a second index, net radiation, to create a more flexible and physically-based version known as the Temperature/Radiation method. Both SRM versions use an index equation to compute snowmelt runoff from the snow-covered fraction of a basin, and can incorporate remotely-sensed data to determine the physical parameters required for model input. This paper compares the results of the temperature Index and Temperature/Radiation methods with observed runoff from (1) a small basin with measured net radiation, (2) a small basin with net radiation estimated form in-situ meteorological measurements, and (3) a large basin with net radiation estimated using publicly available data from on-line sources. The results show that the two versions are comparable in terms of the computed numerical measures of model performance. Therefore, the user could choose between the two methods depending upon the available data. The Radiation/Temperature method reduces the need to vary a critical model parameter throughout the season, and provides a physically-based method to estimate that parameter independent of model input.