The former Techniques Development Laboratory (TDL) of the U.S. National Weather Service began collecting Manually-Digitized Radar (MDR) data in November 1973 from teletype reports for the eastern two-thirds of the United States. In 1978, TDL began archiving the MDR on a new grid aligned with the output grid of the Limited Fine Mesh (LFM) model, which was the model used for numerical weather prediction at the time. The new MDR archive covered the entire conterminous United States. As with the old MDR data, the new data were archived in Model Output Statistics (MOS) predictand format to support thunderstorm prediction. In addition to the "raw" MDR data, TDL also created a gridded 20-nautical-mile-resolution MDR product.