Original Title: Isentropic Analysis And Interpretation Operational Applications To Synoptic And Mesoscale Forecast Problems RevisionA basic review of the isentropic coordinate system, including its advantages and disadvantages for operational use. The primitive equations in isentropic coordinate form are discussed with emphasis on their physical meaning and interpretation. Isentropic analysis techniques for horizontal and cross sectional perspectives are described as aids for diagnostic analysis of synoptic scale weather systems. Numerous diagnostic variables are discussed; all can be excellent tools in identifying synoptic scale features helpful in forecasting cyclogenesis and regions susceptible to strong convection. The final section presents specialized applications of isentropic susceptible to strong convection. The final section presents specialized applications of isentropic techniques to weather analysis and forecasting, including: trajectory analysis, tropopause folding process, short-term forecasting of severe weather threat areas, and aviation forecasting. Keywords: Meteorology, Weather forecasting, Aviation forecasting, Weather analysis, Isentropic analysis, Isentropic coordinate system, Constant pressure analysis, Trajectory analysis, Tropopause folding process, Psi charts, Sigma charts, Thermal wind, Static stability, Vorticity, Condensation pressure, Condensation ratio, Condensation difference, Streamlines, Trajectories, Freezing level, Icing, Clear air turbulence, Overrunning convection. (jhd).