The scattering probabilities for a multiband carrier wave function have been studied for hole transport in 4H-SiC. During the drift at high electric fields it is possible to find the carriers with almost equal probability in two neighboring bands. In contrast to the standard Monte Carlo procedure, a possible interference between the components of the wave function in different bands appears in the calculation of the scattering probabilities when the time between scattering events is short. An important role is played by the overlap integral, which forbids this interference in some regions of the epsilon-k (energy-wavevector) space. We compare the results obtained using the true overlap integrals calculated from the wave functions with the common assumption, in which the overlap integral is assumed equal to one. Different scattering mechanisms, such as polar-optical phonon and intervalley optical phonon are studied. The model includes a spread in energy according to the Heisenberg uncertainty principle at short times. We have calculated the final state probability distribution considering the whole Brillouin zone of 4H-SiC for a particular set of initial states.