 The cyclone was travelling south-southwest at about 14 km/h and crossed over or adjacent to the homesteads on the pastoral properties Mundabullangana, Mallina, Coolawanyah, Hamersley, and Mount Brockman.As cyclone Joan crossed the coastal plain and the Chichester Range only a slow moderation of its intensity seems to have occurred, but as the cyclone crossed the Hamersley Range the available evidence suggests that a rapid weakening took place.Tropical cyclone Joan was the most destructive cyclone to affect the Port Hedland area in more than 30 years.