Syfy’s “Warehouse 13” is getting a third season. After weeks of rumors, the cable network is set to announce a 13-episode pickup. Showrunner Jack Kenny will on board for another round and has signed a development deal with Syfy. During its second season, “Warehouse” averaged 3.4 million viewers and 1.5 million in the adults 18-49 demographic, making it Syfy’s most-watched series this year. The Tuesday night drama, produced by Universal Cable Prods., follows two Secret Service agents who collect dangerous supernatural artifacts.