The Nested Grid Model (NGM) and Medium Range Forecast (MRF) Archive is historical digital data set DSI-6140, archived at the NOAA National Centers for Environmental Information (NCEI). The National Centers for Environmental Prediction (NCEP) of the National Weather Service (NWS) runs a series of computer analyses and forecasts operationally, which use or produce model data. This data set is one of several NCEP sets of model data archived at NCEI. Historical data set DSI-6140 consists of two subgroups of NCEP model data: NGM and MRF for the time period January 1, 1991 through April 15, 1997. Geographic coverage is the 48 contiguous states of the United States of America, plus adjacent waters and southern Canada. Major parameters provided by NGM are ice covered water areas (yes/no), snow covered areas (yes/no), terrain height, mean sea level pressure, convective precipitation, total precipitation, exchange coefficient at surface, upward turbulent flux of sensible heat, upward turbulent flux of water, surface pressure, number of mixed layers next to surface, u component of wind, v component of wind, vertical velocity, specific humidity, and temperature. Parameters provided by MRF are surface temperature, geopotential height, and relative humidity. DSI-6140 is the historical precursor data set to digital data set DSI-6141, NCEP EDAS and GDAS (FNL) Model Data, also archived at NCEI.