Millions of Australians are bracing for “severe” weather, as a high pressure system off the Tasman brings widespread rainfall and flood warnings.

The Bureau of Meteorology has issued alerts for flooding along the Murray River at Barham as early as Thursday.

“Upstream flows from the Murray River, combined with flood waters from the Goulburn River, may cause minor flooding along the Murray River,” a spokesman said.

South Australia, NSW, Victoria and Tasmania are all currently enveloped in a large cloud system which has created multiple fronts and troughs.

Locals have been warned about the possibility of wind and flood damage across north eastern Victoria and north western Tasmania.

“We’ve got this cloud band extending down here from Central Australia that’s pulling in moisture from the tropical Indian Ocean,” a Bureau of Meteorology spokesman said.

“Those catchments in these areas, they’re wet and they’re ready to respond quickly to any rain that falls over the next few days so there’s the current flood warnings.”

The system is set to move east on Wednesday, bringing widespread rain before clearing out on Thursday.

“Over the next few days, large parts of those areas of south eastern Australian are likely to see 10-30mm of rainfall,” the spokesman said on Tuesday.

Wind conditions are expected to reach 60 to 70km/h in the central ranges of Victoria, reaching down to Melbourne and across to Port Phillip Bay.

The Bureau of Meteorology predicted “winds from the north during (Wednesday) with peak gusts up to 90km an hour”.

“We’re expecting the winds to peak through Melbourne in the late morning before easing in the afternoon, but it will broadly be a windy day right across western and central Victoria at first and parts of eastern Victoria later as well.

Many parts of the country expecting rain are in agricultural areas, but Bureau of Meteorology meteorologist Dean Narramore said it would mostly be falling in places which hadn’t been experiencing below-average rainfall.

“Things are pretty green and lush throughout these areas already, so it will be great for some and perhaps a bit too much of a good thing for others, depending on where you are.”

Sydney is expecting showers throughout the week, with average daily maximums ranging between 19C and 22C.

Melbourne is expecting showers from Tuesday through to Saturday, with daily maximums ranging between 17C and 19C.

Adelaide is expecting showers increasing on Tuesday, with conditions easing from Wednesday and clearing up completely by Sunday.

Max weekly temperatures will range between 16C and 19C.

Tasmania can expect a delayed start to their wet weather week, with the high pressure system developing on Tuesday and persisting through to Thursday.

A follow-up trough is expected to pass over on Thursday with rain continuing until Friday.

Hobart’s weekly max temperatures will fluctuate between 14C and 18C with a shower or two expected everyday from Wednesday to Saturday.

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