A near-perfect weather pattern is set to deliver widespread rain across eastern Australia, from Brisbane to Sydney, Canberra, and Hobart, after drenching Adelaide late last week and over the weekend.
Key Ingredients for Rain
For rain to occur, two factors must align: instability and moisture. Currently, both are abundant. Instability is provided by low-pressure systems, marked as 'L' on weather maps, along with troughs (dotted lines) and fronts (lines with barbs). Moisture is drawn from the Pacific Ocean, with high pressure positioned to the south pulling warm, moist air across the southeast of the country.
Weather Pattern on Tuesday
On Tuesday morning, the original low near Adelaide remains, accompanied by troughs over inland Queensland, New South Wales, and the NSW south coast.
Weather Pattern by Thursday
By Thursday, the original low over South Australia has dissipated after nearly a full week. In its place, two new lows have formed: one near the Queensland-NSW border and another just off eastern Tasmania. This slow-moving pattern ensures that showers, storms, and widespread rain continue, with the focus shifting eastward to where the new low-pressure sources are located.
Rainfall Forecast
The most significant widespread rain, with falls of 20mm to 100mm, is expected in southeast Queensland, eastern NSW, and far eastern Tasmania. These areas are closest to both the moisture source and the low pressure. Local falls exceeding 100mm are likely in parts of eastern Queensland and NSW.
However, some areas will see less rain. A band stretching from near Melbourne up to central NSW, and another in western Queensland, NSW, and eastern SA, will likely receive minimal precipitation. Melbourne is expected to be one of the areas with the least rainfall from this system, though foggy grey skies will persist.
Why Some Areas Miss Out
When rain moves around a low-pressure system, it does so in waves, with lines of wet weather causing heavy downpours in one spot while completely missing another. Melbourne is likely to be in one of those drier zones, but the grey, low cloud, fog, and drizzle will make it feel like rain is imminent.
