Geologically and petrophysically constrained synthetic random velocity fields are important tools for exploring (through the application of numerical codes) the seismic response of small-scale lithospheric heterogeneities. Statistical and geophysical analysis of mid- and lower-crustal exposures has demonstrated that the probability density function for some seismic velocity fields is likely to be discrete rather than continuous. We apply the term ''modal'' fields to describe fields of this sort. This letter details a methodology for generating synthetic modal fields which satisfy the von K¿rm¿n covariance function. In addition, we explore some of the mathematics of ''modality,'' and define a modality parameter which quantifies the variation between end members binary and continuous fields.