Australia & New Zealand: Surplus continue in SE Australia, deficits in sW

30 June 2023

THE BIG PICTURE
The 12-month forecast ending in February indicates that Australia will experience widespread mild deficits, with small pockets of more intense anomalies scattered throughout the continent. Non-contiguous areas of the region are expected to observe intense deficits.

Extreme to exceptional deficits are expected in the following regions:

Northern Queensland, in pockets within the Yorke Peninsula, north of the Burdekin River and near Heathlands Regional Park.
Northern areas of Northern Territory, in coastal regions north of the town of Borroloola and northern areas of West Arnhem.
Northern coastal regions of Tasmania.

Severe to extreme deficits are forecast in:

Southwestern Western Australia, throughout coastal regions near the Blackwood and Swan rivers.
Southern Tasmania, in areas surrounding Lake Gordon and Lake Pedder.
Eastern coastal regions of New South Wales.
Throughout New Caledonia.

Areas expected to observe extreme to exceptional surplus include:

Central New South Wales, surrounding regions both north and south of the Lachlan River. Small areas of intense transitional conditions are expected to emerge in the same territory.
Northwestern Victoria, south of the Murray River.
East-central Northern Territory, crossing over into west-central Queensland.
Northern New Zealand, throughout much of the Northland region and continuing in pockets in northern coastal regions of Auckland and the Bay of Plenty.

The 3-month maps (below) show the evolving conditions in more detail.

FORECAST BREAKDOWN
The forecast through August 2023 anticipates widespread mild deficits across the continent, with exceptional surplus persisting in central New South Wales, as well as in northern Western Australia, eastern Northern Territory, and northeastern Queensland. Deficits in southwestern coastal regions of Western Australia near the Blackwood and Swan rivers are expected to intensify into exceptional severity. In non-contiguous areas, exceptional deficits in northern Tasmania are expected to expand in size, reaching some southern coastal areas of the country. New Zealand should observe mostly normal conditions.

From September through November 2023, exceptional surpluses in northern Western Australia, eastern Northern Territory, and northeastern Queensland are expected to continue. Surplus in central New South Wales is expected to shrink in size but remain in exceptional intensity. Deficits in Tasmania are expected to lessen in intensity, returning to moderate to severe deficit. Small, isolated areas of central and southern New Zealand can anticipate mild to moderate deficits.

The forecast for the final months – December 2023 through February 2024 – anticipates most anomalies across Australia to disappear, with exceptional surplus still lingering in New South Wales. Tasmania can expect mild to moderate deficits to endure across the country.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Australia’s weather experts, energy market operators, farmers, and state emergency officials are expected to meet in July to decide whether or not to prepare for an El Niño summer, which may heighten risk of heatwaves, fires, droughts, and power outages. The Bureau of Meteorology predicts the chances of an El Niño happening this year at about 70 percent, classifying the probability to an “alert” warning – the second to last level before confirmation on the bureau’s scale. Topics to be discussed include steps needed to minimize the risks of power shortages, blackouts, bushfires and droughts that may affect public safety, essential services, agriculture, and livestock. The National Oceanic and Atmospheric Administration, which is the Bureau’s equivalent in the United States, has already declared an El Niño summer, based on unusually elevated surface temperatures.

Central and northern Australia are at risk for flooding as a large rain band sweeps across the regions, prompting flood warnings and road closures. Parts of South Australia, Western Australia, and the Northern Territory are being impacted by the seasonally uncharacteristic rainfall, which is expected to hit 100 millimeters in some areas. In Western Australia, the Bureau of Meteorology has announced a flood watch for the Pilbara, Kimberleym and other districts in the interior of the state. "River and creek level rises and localized flooding are possible, however, river levels are expected to remain below the minor flood levels," the bureau added.

Two dams in South Australia are at risk of overflowing amid severe weather across the state. Regional emergency services are monitoring two dams, one south of Adelaide and one in the Hills, for potential flooding.The State Emergency Service (SES) has also issued flood watches and warnings for areas near the dams at Basket Range and Hope Forest. Derren Halleday, SES chief of staff, stated that structural engineers had inspected both dams to gauge their integrity. "As well as the engineer reports, we have personnel physically on-site monitoring and inspecting the dams and their immediate surrounds, and we are also working closely with the Department for Environment and Water,'' he said.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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