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Adelaide on track for wetter-than-average July with more rain to come statewide

Tuesday July 27, 2021 - 01:19 AEST
ABC image
A lone surfer tackles a stormy ocean off Adelaide's metropolitan coast on Saturday. - ABC

Monthly records have been thrown out and Adelaide is about to reach its average rainfall for this time of year as a dramatic turnaround from South Australia's dry autumn continues.

Authorities are still cleaning up after a series of frontal systems brought mini-tornados, power outages, hail, localised damage, big seas, and bucket loads of rain to parts of the state.

For the Yorke Peninsula town of Minlaton, its previous July record of 89.6 millimetres has been smashed with 130.8mm recorded this month so far, while the Barossa town of Greenock recorded 119mm ? quashing its previous July record of 91mm.

In Adelaide, 82.6mm has fallen this month ? well above the July average of 65.9mm ? and the city is on the cusp of reaching its average annual rainfall level to the end of July by being just 0.3mm shy of receiving 313.7mm to date.

Bureau of Meteorologist Naomi Benger said the strong rainfall, which began in June when Adelaide received above average monthly rainfall of 106.4mm, could be linked to a negative Indian Ocean Dipole (IOD) event.

"That means there's a difference between the sea surface temperature anomalies in the eastern and western parts of the Indian Ocean," she said.

"We currently have warmer waters off the north-west shelf of Australia, those waters south of Indonesia, and while that does seem far away it actually funnels extra moisture into the atmosphere that makes its way down across our region."

Ms Benger said that as strong frontal systems passed over the state they could "tap into that moisture and deliver it as above average rainfall".

More wet weather to come

It follows an autumn where rainfall across South Australia as a whole was 20 per cent below average, despite some parts of the north, such as Hamilton and Tieyon stations, receiving record rainfall for the season.

Ms Benger said the bureau was forecasting the wet weather to continue with a wetter-than-average July and the IOD to remain in a negative state until around the middle of spring.

"It's difficult to predict exactly when that rainfall will come and whether it will come as a series of fronts or a rain band, but certainly managing water on a larger scale, farmers can expect a healthy amount of rainfall across the Murray-Darling Basin," she said.

Ms Benger said added that it was "tricky" at this stage to say what would happen from Spring.

"But it's not like you turn off a tap. It's not going to dry up quickly," she said.

Reservoirs filling

SA Water's reservoirs too are in a much better position than at this time last year, though with total storage levels at 61 per cent ? compared to 50 per cent at this time in 2021 ? its largest are some way from capacity.

The biggest at Mount Bold is currently at 25.5 gigalitres, or 55 per cent capacity of 46.4 gigalitres, well up on this time in 2020 when levels were at just 24 per cent and above its July average of 14.8 gigalitres.

The next biggest at South Para is at 23.6 gigalitres, or 53 per cent of 44.8 gigalitres, up from 42 per cent this time last year and above its July average of 20.4 gigalitres.

The Barossa and Myponga reservoirs are at 93 and 94 per cent respectively.


© ABC 2021

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