1. An electronic display processor for an avionic weather radar system comprising: at least one input for receiving electronic aircraft data providing aircraft heading, and for receiving radar scan data providing for echo information at a plurality of scan angles and ranges; at least one output for outputting a graphical representation of at least a onion of the radar scan data mapped to a display angle and display range; and an electronic computer communicating with the input and output devices and executing a stored program held in non transient media to correct the display angles of echo information in the graphical representation for given radar scan data to differ from the scan angles of the given radar scan data, the correction befit according to a change in a heading of the aircraft between a time of acquisition of the given radar scan data and a time of outputting of the graphical representation of the given radar scan data.