Surely there must be witnesses on the ground at or around YMTG around the departure time of this flight. Not a witness of the departure, but a general description of the actual weather at the time. The METAR indicates 200' cloudbase and 3km viz, and maybe the Rex crew noticed something, or even the refueller? Air Services had live cameras filming the four quadrants at the time, I wonder whether these still pictures are recorded? I wonder what the AWIS (133.425) information was at the time, and is this data recorded?
Live Weather Cameras | Airservices