A new suite of digital, 1-km2 gridded snowpack information products called the National Snow Analyses (NSA)is described. The NSA are being produced experimentally for the coterminous U.S. by the National Operational Hydrologic Remote Sensing Center, National Weather Service, NOAA (www.nohrsc.nws.gov). The NSA consist of a comprehensive suite of gridded data sets describing snow water equivalent, snow depth, snow surface temperature, snowmelt, and other snowpack characteristics. The high-resolution NSA provide an important new source of information for weather, water, and climate forecasters, and for managers and decision-makers responsible for agriculture, water resources, fisheries, and hydroelectric power production. The NSA are produced using a nested, uncoupled multi-layer snow and soil model that is forced by downscaled hourly mesoscale numerical weather analyses. The snow model is updated daily using all available ground, airborne, and satellite-derived snow information. This paper focuses on issues associated with the fusion and assimilation of multiple and often disparate sources of snow information, and underscores the need for a more coherent global snow observing system.. Results from the recent Cold Land Processes Field Experiment help illustrate the large spatial variability of snowpacks and the resulting challenges for climate, water, and weather modeling and assimilation.