On December 23, the Joint Typhoon Warning Center (JTWC) reported that a tropical disturbance had developed within the monsoon trough about 1540 km (960 mi) to the east of Medan in Indonesia [REF].
Early on December 26, the IMD reported that the depression had intensified into a Deep Depression, before later that day reporting that it had intensified into a cyclonic storm and named it Thane [REF].