A TROPICAL low sitting off the coast could soak Central Queensland with up to 500mm of rain by Tuesday - the biggest drenching in 20 years - if cyclone modelling proves accurate.
Bowen and Mackay are likely to be hit hardest by the system, currently north-west of Cairns, with boffins expecting it to evolve into Cyclone Gillian, a Category One system on Sunday morning.
It is then forecast to edge towards the coast.
Current predictions have it making landfall between Townsville and Mackay either late Sunday or Monday morning.
If that happens, Mackay and Bowen can expect winds exceeding 90kmh as Rockhampton is hit with gusts reaching up to 60kmh.
Up to 300mm of rain could drench the region in the 24 hours spanning Sunday and Monday as seas rise above the 4m mark.
Weatherzone meteorologist Ben McBurney said winds and rain from the low and emerging cyclone will make for a wet and windy weekend for Bundaberg, Hervey Bay and parts of the Sunshine Coast.
"The rainfall totals could be from 300mm to 500mm - it would be the best rain for those areas for about two decades," Mr McBurney said.
"The biggest impact from the system will be rain, it's a slow moving system and could linger off shore if it doesn't cross the coast earlier."
Queensland's State Disaster Co-ordination Centre will be ramping up their monitoring of the emerging cyclone from 6am Saturday.
Meanwhile, a second cyclone is likely to form near Cape York, in the Gulf of Carpentaria.
This second system - likely to be named Hadi - will be less intense and will likely disintegrate after reaching the Cape.
There is a distant chance Hadi and Gillian could collide, but Mr McBurney said this would lead not to a super-powerful storm, but more likely the pair would destroy one another.
For ongoing updates on the emerging cyclones, visit http://www.bom.gov.au/cyclone.
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