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In this article, we use the analytical Kirchhoff solution (AKS) and numerical Kirchhoff approach to study the bistatic scattering field ($\gamma $) from mountain terrain at P-band frequency. The study area is Grand Mesa, Colorado, USA, and the properties of land surface roughness are extracted from airborne lidar surveys. The bistatic scattering coefficient $\gamma $ of variance fields, denoted by${\gamma }_v$, for several cases of radar resolutions over a 3.6 km by 3.6 km area are calculated at various scattering azimuth angles. Based on the lidar measurements, the land surface is decomposed into ${f}_2 + {f}_3$, where ${f}_3$ is 30 m of deterministic planar patches to approximate the coarse topography and ${f}_2$ is modeled by random rough surfaces with correlation functions. Surface roughness statistics derived from the Lidar data give a typical root mean square height of 0.07 m and a correlation length of 3.6 m for ${f}_2$. The mean values of slopes of ${f}_3$ are 1.3° and 0° with a standard deviation of 1° each, respectively in the x and y directions. Simulations using AKS show that the values of bistatic scattering coefficients for the variance of scattered fields can reach above 10 dB over a range of azimuth angles ${\phi }_s$ in the vicinity of the specular direction. Even in mountainous regions, the value of the ${\gamma }_v$ around the forward scattering direction is much larger than that for radar backscattering, and thus could support the use of a synthetic aperture radar concept based on signals of opportunity with data acquisition near the forward direction.