Tropical Cyclone Oswald (2013) is considered to be one of the highest impact storms to make landfall in Australia although its lifetime maximum intensity only reached category 1. After landfall over the Cape York Peninsula, its remnant lasted for more than 8 days over land moving parallel to the coastline as far south as 30ºS. When Oswald moved southward to Cairns and Townsville on 23-24 January, its circulation was supposed to weaken rapidly because of the lack of underlying energy supply from the warm ocean, the surface friction and the enhanced topographic barrier. However, the remnant of Oswald re-intensified and maintained until 25 January, and caused widespread extreme rainfall during the passage of a mid-latitude trough. After a short intermittent period, Oswald slightly re-intensified again near Rockhampton and experienced another extended heavy rainfall as the approaching of the second mid-latitude trough on 27 January. The two mid-latitudes troughs contribute to the long-duration Oswald’s circulation over land and unusual heavy precipitation from 23 to 28 January. In this presentation, to better understand how this weak tropical cyclone can produce such widespread impacts, we will show detailed trajectory and diagnostic analysis to investigate the physical mechanisms during the two TC-trough interactions that caused Oswald’s circulation to re-organize over land.