The Finnish Meteorological Institute and the Vaisala meteorological measurements company, together with other public, private, and academic partners, initiated plans for a new mesoscale observation network tested in southern Finland. The testbed, called Helsinki Testbed, is an open program, and collaborators are encouraged to participate. It will provide new opportunities for measuring, studying, and predicting atmospheric processes and applications in a high-latitude coastal environment encompassing southern Finland. The program seeks to enable and promote testing of scientific theories, new technologies, and end-user applications.