High hopes New South Wales deluge will bring drought relief to inland farmers

Australia Broadcast Center

21-05-2025

There is high confidence the soaking along the NSW north coast will shift south in coming days and bring drought relief to parts of the Murray Basin.
However while inland farmers rejoice, flooding will become more widespread across the Hunter and Mid North Coast as another 48 hours of heavy rain flows into already swollen rivers.
And while South Australia and western Victoria will miss out on the initial rainband, a vigorous cold front will bring widespread showers to Australia's southern coastline from Sunday to Tuesday — along with a burst of ferocious winds likely to trigger multiple severe weather warnings.
Record May rain has already fallen on several locations in New South Wales, between Port Macquarie and Dungog, this week.
For Taree, 279 millimetres in the 24 hours to 9am Tuesday was a May record, and less than 25mm off an all-time record.
The rain around Taree was so intense overnight, the Manning River rose upstream as much as 12 metres in just over 12 hours, prompting a major flood warning.
The Hastings River was also placed under a major flood warning after Port Macquarie was drenched by 239mm in 24 hours — also a May record, and the city's heaviest rain in any month since 1974.
Rain continued to tumble down through Tuesday afternoon across the Upper Hunter and Mid North Coast, also triggering major flood warnings for the Paterson, Williams and Gloucester rivers.
Modelling indicates heavy rain will persist all through Wednesday from about Yamba to the Central Coast as an onshore airstream off the Tasman Sea feeds moisture into a near stationary trough.
For the waterlogged Mid North Coast and Upper Hunter, totals could again easily exceed 100mm in the next 24 hours.
The rainband should then edge slowly south on Thursday with heavy falls extending from the Mid North Coast to possibly Sydney and the Illawarra, but again it is the already flooded regions in the north which are likely to face the most intense downpours — possibly a fourth consecutive day with over 100mm.
The rainband will then accelerate south on Friday and bring moderate falls to the South Coast of NSW, while sunshine reappears over the sodden catchments further north.
As the deluge continues on the coast today, a new weather system will enter the frame and interrupt the stagnant pattern.
A low-pressure system above the surface will drift over the south-east inland, and since winds blow clockwise around a low, its presence is what will drag the coastal rain south over the coming days.
Critically, the upper low's position is far enough west to also pull moisture over the ranges, setting up the right conditions for rain over parts of the Murray Basin.
The first showers should arrive over the Central West and Riverina later today, before expanding across much of western NSW on Thursday east of about Ivanhoe.
Showers should then continue on Friday across southern NSW, while also spreading to central and eastern Victoria.
How much rain will fall? This event is quite complex, and has numerous moving parts — hence the sudden upgrade from possible showers to a more solid rain event.
In general, between today and Saturday, modelling is indicating falls between about 10mm and 40mm across most of the NSW Central West, Southwest Slopes, and Riverina, along with the North East district of Victoria.
For areas fortunate enough to receive totals near the higher end of this range, the event will constitute the long-awaited autumn break and should be the heaviest soaking in at least a few months.
However, with nine-month rain deficits in the range of 75mm to 300mm across much of the southern Murray Basin, this one event will require several follow-up falls before drought severity is considered to have eased.
Further south, totals over Victoria's Northern Country and Central North regions are likely to display even greater variability ranging from zero to 20mm.
The moisture and rain along the eastern seaboard this week will not reach SA or far western Victoria, however a powerful cold front due to arrive on Sunday and Monday offers some hope of relief.
The best rain from cold fronts, particularly for inland regions, occurs when they link with a stream of tropical moisture and are preceded by a continental scale cloudband.
Unfortunately the much-desired pre-frontal rain will be absent ahead of the front, however the system should be strong enough to deliver moderate falls to the coast and adjacent ranges.
For areas of the coast exposed to westerly winds from the bottom of Eyre Peninsula to Wilsons Promontory, at least 20mm should fall — and that includes around Kangaroo Island, Mount Gambier, Warrnambool and Wonthaggi.
Totals will then drop off over the ranges and at this stage the Riverlands, Murraylands, Wimmera and Mallee are unlikely to see anything more than a millimetre or two.
The front will also lead to at least 48 hours of strong winds, and warnings are likely for damaging gusts over a broad swathe of southern Australia with peak speeds easily exceeding 100 kph in multiple regions.