Sydney weather; 'Substantial' rain to end relatively dry spell

Brolly time: get set for the wettest spell in more than a month as a large low pressure system sweeps across southern Australia.
Brolly time: get set for the wettest spell in more than a month as a large low pressure system sweeps across southern Australia.

Sydney's sparkling mid-May conditions will make way later this week for the city's wettest spell in more than a month as a large low pressure system sweeps across southern Australia.

The good news, though, is both Wednesday and most of Thursday should remain dry and there is no sign of a cold front to knock temperatures back to average levels for May.

"We'll definitely get some substantial rain compared to what we've been seeing," Rob Sharpe, a meteorologist for Weatherzone, said.

"This is going to bump us up a bit.”

Rain soaking South Australia and parts of Victoria on Tuesday will reach Sydney by Thursday. Photo: Himawari-8

Rain soaking South Australia and parts of Victoria on Tuesday will reach Sydney by Thursday. Photo: Himawari-8

Half way through May, rainfall totals in Sydney are shy of 15 millimetres - a fraction of the typical monthly falls of about 120mm.

The last big falls came about six weeks ago, when 34mm was recorded at Observatory Hill.

While showers will feature late on Thursday and Friday, Saturday looks to be the wettest of the coming days with 15-30mm expected in the eastern suburbs.

The west should receive 10-15mm on that day, Mr Sharpe said.

The Bureau of Meteorology has a lower forecast for the rain event, tipping only 3-8 mm for Sydney on Saturday in its updated forecast.

"We'll definitely get some substantial rain compared to what we've been seeing."

Rob Sharpe, meteorologist for Weatherzone

That's down from a range of as much as 25 millimetre in an earlier report.

The falls could be a lot heavier to Sydney's south and north, as coastal NSW comes in for a heavy soaking on Saturday.

(See chart below from the Bureau of Meteorology, showing expected rainfall totals for NSW on Saturday).

For Sydney and inland regions of NSW, the rainfall will be mostly from the slow-moving low pressure trough.

Further north, though, rain will be more intense, as the trough draws in moisture from the Coral Sea, Mr Sharpe said.

Areas such as the Mackay region of central Queensland and inland areas could get unseasonable falls of 50-150 mm, he said.

The bureau issued a flood warning on Tuesday for regions between Cairns and Gladstone, with isolated falls of as much as 400 mm possible.

What's missing from the set-up is a cold front, so day time temperatures will continue to top 20 degrees or warmer in Sydney.

From Sunday, the mercury is forecast to reach tops of 23 degrees for three days in a row, the bureau predicts. 

After another chilly night going into Wednesday, with a minimum of 11 degrees forecast for Sydney, overnight temperatures will become milder as the clouds and rain arrive.

"At this point, there are no strong indications of a cold front moving across NSW any time this month," Mr Sharpe said.

"Anyone hoping for early snow in the alps will probably be disappointed," he said.

Weatherzone is owned by Fairfax Media, publisher of this website.

The story, Sydney weather; 'Substantial' rain to end city's relatively dry spell, first appeared on the Sydney Morning Herald.