The lattice Kerker effect refers to a strong suppression of reflected light from periodic arrays of scatterers in narrow spectral windows at normal incidence. It can occur when interference of scattered light from different multipolar modes from each unit cell and diffractive coupling among unit cells occur simultaneously. Here we investigate manifestations of the lattice Kerker effect in 1D arrays of planar plasmonic oligomer trimers. Numerical results computed using a coupled electric dipole model for 1D non-Bravais trimer arrays, where the three constituent particles in each trimer unit cell are explicitly included, are rationalized using a coupled electric and magnetic dipole model on a 1D Bravais lattice. This model allows the differential scattered power angular distributions from the array to be decomposed into the product of the angular distribution produced by a single unit cell containing colocalized electric and magnetic dipoles and the squared modulus of a structure factor accounting for diffraction arising from the periodic array. In addition to providing an intuitive explanation for characteristic signatures of the lattice Kerker effect at normal incidence, this model also enables the facile evaluation of angular scattered power distributions for non-normal angles of incidence. The results of this work expand the concept of the lattice Kerker effect in terms of both unit cell design and excitation conditions and provide a simple analytic model for designing periodic structures with engineered properties for applications in nanophotonics concerned with highly directional radiation beaming and enhanced magnetic field strengths at optical frequencies.