Parts of the southern Queensland town of Dalby have been evacuated as floodwaters inundate homes.
Emergency Services are on standby across much of central and southern Queensland where constant heavy rain is causing road chaos and flash flooding.
The Bureau of Meteorology says the combination of an upper-level low and a surface trough have brought thunderstorms and moderate to heavy rainfall to the region as it moves across the state.
On Saturday afternoon the Western Downs Regional Council warned up to 30 homes in Dalby would be flooded if the Myall Creek reached a forecasted three-metre peak at midnight.
But the water arrived several hours earlier than hydrologists expected.
Local Mayor Ray Brown says the creek reached more than three metres at 8:30pm (AEST) and some homes and properties have been flooded.
"The latest is about 3.16 metres and still rising," he said on Saturday night.
[The weather bureau] revised the prediction at 3.2 metres. It is just about that now. It is still rising.
"There is some concern there. Obviously, residents are well aware of what's occurring but there is significant water through the town right now and certainly access along the Warrego Highway is down to a single lane at a time."
The weather bureau says the Myall Creek will peak at 3.2 metres overnight.
Lockyer Valley alert
Meanwhile, an emergency alert was issued in the Lockyer Valley, west of Brisbane, on Saturday night.
The local council says flooding is expected at Forest Hill, Laidley, Glenore Grove and areas downstream.
Residents are being urged to monitor the situation and leave their homes if necessary.
All across the south east the wet conditions have cause road closures and accidents, but no homes have been flooded.
Authorities are desperately urging motorists to avoid flooded roads.
The downpour has cut roads from the central coast to Tweed Heads, and inland to the Darling Downs and Granite Belt.
© ABC 2013
12:38 EST Tropical Cyclone Jack has rapidly developed over the warm waters of the Indian Ocean in the past 24 hours, making it the 10th system to be named this season.