This dataset contains various gridded Northern Hemisphere tropospheric analyses and 6-hour forecasts produced by NMC's operational model for the period October 1958 to December 1972. Vertical motion analyses at 650mb and 350mb are available for most of the period, and geopotential heights and thicknesses for for various levels and layers are available until January 1965. Six-hour forecasts of vertical motion cover the period from July 1966 to December 1972. The grid is a 47x51 polar-stereographic grid centered on the North Pole.