The probable location of petroleum deposits is determined by identifying a severe-weather-inducing site from severe weather such as mesocyclones, tornados, funnels aloft, wall clouds or supercells, water spouts, and a high density of multiple lightning ground strikes. Typically the severe-weather-inducing site is located by identifying the initial appearance of the tornado vortex signature in modern Doppler radar or monitoring the severe weather, recording data as to its position and its velocity and acceleration with respect to the ground or water surface if it is moving, and determining the inducing site from such data. The occurrence of multiple severe weather sites in a dense pattern is also used to determine the probable location of petroleum deposits.