The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of the key instruments onboard the Suomi National Polar-Orbiting Partnership (Suomi NPP) spacecraft. The snow cover product consists of several data layers including a normalized-difference snow index (NDSI) snow cover map and quality assessment data.  The VIIRS algorithm was adapted from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 (C6) snow-cover algorithm and data products, thus leveraging analysis and evaluation from both to make nearly-identical algorithms and similar data products for eventual production of a climate-data record.