We show that the general solution to a simple form of the simultaneous bimodal (radial and pitch angle) diffusion equation can represent the SCATHA outer belt electron distribution to a high degree of accuracy for periods up to about 10 hours. The data representation requires diffusion parameters that are in agreement with all previous experimental and theoretical determinations of such diffusion coefficients. Such a representation satisfies the basic requirements toward the dynamic modeling of the outer electron radiation belts for L<7 at quiet and moderate geomagnetic conditions. For L~7 the representation has difficulties with ''butterfly'' distributions that may signify energetic electron encounters with the magnetopause or severe shell splitting. ¿ American Geophysical Union 1990