AUSTRALIA & NEW ZEALAND: WATER DEFICITS PERSIST IN TASMANIA

21 March 2018

THE BIG PICTURE
The 12-month forecast (below) continues to show exceptional water deficits in Tasmania and along Victoria’s southeastern coast. Moderate deficits lead from Adelaide north, becoming exceptional along the northern border of South Australia and New South Wales. Intense deficits are forecast for parts of northern Queensland to the Gulf of Carpentaria.

A broad path of moderate to severe deficit is forecast in the middle of the country from central Northern Territory through South Australia. Deficits of similar intensity are also forecast for the area surrounding Darwin, NT, and along the east coast from Brisbane to Sydney.

Surplus is forecast for West Australia’s Kimberley region, and in the opposite direction in eastern Queensland around the Mackenzie River and west of Bundaberg.

Deficits of varying severity are expected in pockets of New Zealand and moderate deficits are forecast for New Caledonia.

FORECAST BREAKDOWN
The 3-month maps (below) for the same 12-month period show the evolving conditions.

As is readily apparent in the map series above, the forecast indicates a dramatic transition from widespread exceptional deficits to predominantly mild conditions. The near-term forecast through May indicates the persistence of moderate to exceptional deficits in Tasmania, particularly in the west. Primarily moderate deficits are expected in eastern South Australia, throughout much of Victoria, in the Murray-Darling Basin, and northward along the east coast to Brisbane. Moderate to severe deficits are forecast to persist near Busselton, West Australia, and emerge farther north surrounding Minilya, WA. Scattered pockets of moderate deficit are forecast for the Ord River Basin in northern WA, around Daly Waters in Northern Territory, and in northern Queensland. Surplus conditions will persist in the Kimberly region of WA; shrink along the Victoria River and emerge in Arnhem Land in northern NT; re-emerge in northern Cape York Peninsula, Queensland; and continue to emerge in the Mackenzie River area west of Rockhampton, QLD.

Deficits in New Caledonia and New Zealand will moderate.

From June through August merely mild water deficits are forecast for much of Australia with some moderate deficits across the north, near Busselton WA, and along Victoria’s coast. Surpluses will diminish but persist in Kimberly WA and near the Mackenzie River in northeastern QLD. In Tasmania, deficits will downgrade but moderate to extreme conditions remain in the forecast. New Caledonia will return to near-normal conditions. Deficits are forecast for western North Island, New Zealand and along South Island’s southern coast; surplus is forecast near Christchurch.

The forecast for the final months – September through November – indicates conditions similar to the prior three months.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
A state of emergency was declared across four regions of New Zealand after former Cyclone Gita downgraded to a tropical storm and lashed the country in late February. Landslides cut off thousands of people in South Island, and flooding caused evacuations, school closings, and power outages. A state of emergency was declared in many areas and the military was deployed to assist. As reported here last month, Gita slammed the pacific island nation of Tonga as a category 4 storm before proceeding toward New Zealand.

Cyclone Kelvin hit Western Australia’s Kimberley region last month with record-breaking rainfalls, which drove the coastal town of Broome's cumulative 2018 rainfall amounts above the annual average. Flooding cut off parts of the Great Northern Highway nearby, prompting authorities to conduct evacuation and airborne supply deliveries in affected communities.

In the following days Australia’s eastern coast was hit with a system of heavy rain, causing flooding and road closures. Brisbane experienced its heaviest February rain in 28 years, with 136 mm (5.4 inches) in 24 hours. Farther north, the coastal canefarming towns of Ingham and Halifax flooded as the Herbert River breached its banks, leaving 72 children isolated at a school camp and over 200 homes inundated.

In contrast, the pastoralist Gascoyne region of Western Australia is reeling from the effects of a crippling drought, with some stations reporting no meaningful rainfall for three years. Cattle breeders are selling breeding stock and destroying stock, as they struggle to supply adequate feed.

Bushfires fueled by hot, dry conditions raged through the rural southeast in New South Wales and Victoria, destroying 100 homes, forcing the evacuation of 700 residents, and leaving 20,000 without power. Described by a local fire official as "the perfect storm," the fire jumped rivers, benefiting from a combination of strong winds, hot temperatures, low humidity, and dry bush.

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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