This report documents the data reduction procedures used for processing the mesoscale rawinsonde data obtained during Project Stormy Spring. Temperature and humidity data at each pressure contact (about each half-minute) and azimuth and elevation data at either two or ten times per minute were entered on punched cards. The 50-mb layer data for a series of soundings at one station were computed and used in another program to compute local time derivatives and single-station thermodynamic vertical velocities. Data at numerous isobaric and isentropic levels were obtained by interpolation. Data output took a variety of forms including: listings of soundings, time sections, isobaric and isentropic plane sections, mechanical plots of soundings of Skew-T log P diagrams, time traces, punched cards, and magnetic tapes. (Author).