From my time living in NT about a decade ago I can confirm that its relatively low power + the naturally crap performance of AM in the tropics = a range of only about 100km max out of Jabiru. I noticed that up that way the AM stations (at least from what I experienced driving around in my fairly new Pajero at the time) have a distinct whining noise before the static takes over when driving away from transmitter, making them fairly unlistenable way before would normally be experienced in Perth, Adelaide, Melbourne etc.
This plus the relative lack of ABC Darwin FM repeaters in remote communities is why I’m so glad that ABC Darwin mentioned they are broadcasting on the TEABBA network during this cyclone event.