The paper addresses the problem of Dynamic Line Rating (DLR) estimation for OverHead transmission Lines (OHLs) in the context of Wide Area Monitoring Systems (WAMSs). DLR is universally recognized by experts from academia and industry as one of the most viable solution for a reliable exploitation of the real power systems thermal loadability margins. In this domain, the large quantity of synchronized data acquired by WAMSs allows to design effective solution frameworks for DLR assessment. To address this issue, various technical challenges, and many open problems, mainly deriving by the non-idealities characterizing the real working domain, should be fixed. Armed with such a vision, this paper, starting from a comprehensive analysis of the role of synchronized data in OHL DLR estimation, proposes practical and viable solutions aimed at addressing some of the open problems in WAMS based DLR. Experimental findings obtained from in-field investigations on a real life OHL, are presented and discussed in order to prove the effectiveness of the proposed techniques.