For planewave propagation in a random continuum, the changes in mean‐square amplitude and phase variations are derived due to the presence in the medium of a large spherical object arbitrary in density and refractive index, and positioned on the transmitter‐to‐receiver line‐of‐sight. The random continuum is taken as statistically homogeneous and isotropic in space with weak, large‐scale refractive‐index variations representable by a Gaussian autocorrelation function. Calculations are performed for far‐field observation of the forward‐scattered fluctuating signal.