Using level-II WSR-88D data and airborne dual and quad-Doppler measurements, the locations of the spiral descents were characterized with respect to the locations of the leading convective line, transition zone, trailing stratiform region and rear inflow jet. Spiral descents were also categorized according to the relative age of the MCS and strength of the rear-inflow jet. After identifying the spirals in this manner, derived microphysical parameters such as mass content, total number concentration and the derived slope parameter of analytic fits to the observed size distributions, were compared and contrasted for all spirals. From these radar and microphysical analyses, we have synthesized a conceptual microphysical model of the trailing stratiform region of MCSs. This model will be the focus of this presentation.