Colloidal particles provide an efficient means of building multiple scale structured materials from colloidal dispersions. In this Brief Report we account for xperimental evidence on the formation of a colloidal cluster array at a three-phase contact line. We study the influence of low frequency external alternating electric fields on a diluted colloidal dispersion opened to the air. We focus on the cluster formation and their evolution in the meniscus by measuring characteristic times and lengths. We observe that the clusters are separated by a well-defined length and that, in our xperimental conditions, they survive between 5 and 15 min. These new results could be of technological relevance in building tailored colloidal structures in nonpatterned substrates.