Widespread rain is on the way over the next few days over large parts of southern QLD, NSW, the ACT, SA, Victoria and Tasmania.

A pair of troughs are broadening over SA on Sunday, forming into rainbands. These bands of thick cloud and rain are drawing moisture in from the northwest shelf of Australia, an area that is currently experiencing the brunt of the monsoon trough and a tropical low.

With the source of moisture set up, an atmospheric ‘river’ helps direct the humid air into the troughs, which then cool the air and force it to fall as rain.

Image: Precipitable Water at Monday 5pm EDT shows moisture (purple/blue shading) flowing from the northwest over the southeast

Many places in the southeast are expecting moderate falls of 10-20mm. On Monday, the heaviest falls are expected over northern NSW, with widespread 20-40mm expected and isolated pockets of more than 80mm.

Overnight Monday into Tuesday, a complex low pressure system looks to form over Victoria, producing heavier falls as the low transitions over the Tasman Sea. 

With the added moisture and strong winds coming in from the Pacific Ocean, the heaviest falls look to be around central and eastern parts of Victoria, northeastern Tasmania and the NSW South Coast. At the same time, the atmospheric river will flow strong over southern QLD and northern NSW. All of these areas can expect around 20-40mm of rain on Tuesday, with isolated falls of more than 100mm. 

Image: Forecast Accumulated rainfall until 11pm Tuesday

This heavy rain can produce flooding, particularly over the still swollen rivers in northeastern NSW. The northeast corner of Tasmania and central Victoria (including Melbourne) are also places to watch for possible flash-flooding. With the potential for conditions to change quickly, visit here for all the latest warnings.