Abstract: A system and technique is disclosed for estimating the real-time spectral width of radar returns to provide an indication of weather turbulence. The system includes a Doppler radar to provide the in-phase and quadrature phase signals from successive range returns which are digitized and converted to a phase angle prior to processing. Successive angular samples at the pulse repetition frequency are subtracted to provide a phase angle change. The phase angle change is filtered to determine an average angular mean which is then subtracted from new angular samples to determine the angular deviation. The angular deviation for each sample is in turn compared with a threshold to provide an output which is averaged over time to determine when the standard deviation of the samples exceeds a reference value. When the standard deviation of the samples exceeds that reference value, the spectral width is of a magnitude which indicates the presence of turbulence.