A desert deluge is underway in the west while the east is getting a few days of relative calm — but enjoy it while it lasts, because things are expected to get thoroughly wet again later next week.
Bureau of Meteorology forecaster Jonathan How said the widespread showers and storms drenching the north-west of the country were highly unusual.
"To give you a bit of context, the average September rainfall for many of these areas is less than 10 millimetres or so," he said.
"With these storms, many places got that overnight."
The RAAF base at Curtin received 33mm yesterday.
The average September rainfall at Curtin is 0.1mm and before now the wettest September topped out at just 1.8mm.
"So with that just one thunderstorm rolling through they have set a new September record," Mr How said.
Records at Curtin only go back to 1989, but it is very early for rain in the tropical north-west.
Mr How said the rain was a manifestation of the combined affects of the negative Indian Ocean Dipole and La Niña.
Both mean warm waters around the north of Australia and an increased likelihood of an early start to the northern wet season.
A flood watch is in place for the Kimberley and the interior of Western Australia.
'Dreary' long weekend
The low pressure system that brought heavy rain to the east earlier this week has now moved offshore.
In its wake, hazardous surf and showers remain, but it is looking like there will be a relatively calm few days ahead for the east coast.
"Generally the pattern into the weekend – and long weekend for some people – is showery along the New South Wales coast," Mr How said.
The showers are expected to push into south-east Queensland on Saturday.
So while it might still be wet for some, it should hopefully be a bit of a break from the heavy rain and storms.
"It's looking just to be a bit more of a showery, dreary sort of weather pattern for the coast," Mr How said.
But the wet weather is set to ramp up again next week.
'Potentially dangerous'
The east coast has had plenty of rain over the last few weeks, but the next system has got meteorologists concerned.
"This one is looking to be the most significant of the of the lot," Mr How said.
"It's not only got that moisture that it's picked up from the Indian Ocean, but also as it moves across the continent it's picking up moisture from the east as well."
The double source of moisture means the rain is expected to be widespread, but where the heaviest falls occur will depend on where the trough and low pressure system end up moving.
"The forecast will firm up into next week, but it's generally looking pretty wet and potentially dangerous, especially in the second half of next week," Mr How said.
The forecast suggests showers and storms are likely across eastern WA, the Northern Territory and western South Australia on Friday and Saturday.
The rain activity is then expected to gradually creep towards the east over the long weekend.
"By Tuesday night we're looking at fairly widespread showers and thunderstorms all the way from the Top End through western Queensland, western NSW into SA," Mr How said.
"Wednesday is going to be the peak day, with the trough lying through south-west Queensland, inland NSW and then into Victoria and SA."
More rainfall will likely result in renewed or prolonged peaks in many of the rivers already experiencing flooding.
"With this expected rainfall, particularly through southern Queensland, central and western NSW and possibly even northern Victoria, we will be seeing rivers rising again from the middle of next week," Mr How said.
Storms and showers are expected to continue all the way until late next week.
"That will create dangerous conditions for those out there," Mr How said.
As usual, stay safe out there, folks — keep up with the warnings and follow the advice of your local emergency services.
