The approach of a steady state case is being suggested and grounded for numerical investigation of the filamentation at propagation of a high-power femtosecond laser pulse in the turbulent atmosphere. This approach is based on the model of phase screens with the spatial spectrum of refractive index fluctuations covering the inertial and dissipative ranges. This approach can be used in analyzing spatiotemporal traces of hot spots in the pulsed laser beam cross section, which cause the formation of a bunch of random filaments, and in studies of the statistical characteristics of this bunch.