Torrential rain will wash the east coast of Australia this week, potentially triggering major flooding.
The heaviest rain will target the coast and eastern slopes of northeastern New South Wales between Thursday and Saturday.
Parts of the at-risk area were struck by extreme rainfall and record flooding during the last week of January.
Already, as of Tuesday, rainfall over two to three days was as high as 30 cm (12 inches) in southeastern Queensland, and 20 cm (8 inches) in northeastern New South Wales, weather observations of the Australian Bureau of Meteorology (BoM) showed. BoM Flood Warnings were posted for the Mary River, near Brisbane.
BoM Flood Watches for minor to major flooding were in place as of Tuesday for eastern watersheds between the Hunter Valley and the Queensland border.
Forecast tools available to AccuWeather.com suggest that top rainfall in eastern and northeastern New South Wales can reach 25 to 50 cm (about 10 to 20 inches) by Saturday. Heaviest rainfall is forecast to fall north of greater Sydney.
Subtropical low pressure looms off eastern Australia near the border between Queensland and New South Wales. This low, which unleashed heavy rain near the coast on Monday, will make landfall in New South Wales after midweek. (image credit: Australian Bureau of Meteorology)
The likely trigger for the torrential rains would be subtropical low pressure, hovering off shore east of Brisbane on Tuesday. This low is forecast to strengthen and back southwestward, beginning Thursday, thereby giving heavy rain as well as strong coastal winds.
The destructive late-January rain and floods came in the wake of a former tropical cyclone, being Oswald. Oswald landed on the Cape York Peninsula of northern Queensland, loosing cyclone status. Yet the rainy weather system held together as it drifted southward over eastern Australia, unleashing extreme rainfall and flooding as far south as Sydney.
The plum rains are known as "meiyu" in China, the "baiyu" or "tsuyu" in Japan, and the "jangma" in the Koreas. The heart of the plum rain season stretches from early June to mid-July, with a tendency to shift south to north across the affected area.
In the wake of the mid-June cloudbursts, most of Pakistan to northwestern India last week saw a return to dry, hot weather typical of the weeks leading up to the Monsoon onset. It was as if the Monsoon withdrew to its "normal" position for the latter half of June.
The 38.5 degree C (101 degrees F) reading Tuesday in Ajaccio, Corsica, may have been tops in Europe.
Monsoon Onset was June 13th, 2013, in Delhi, almost two weeks earlier than average. The June 15th onset at Karachi and Islamabad was more like three week ahead of schedule.
In Pakistan, hit-or-miss downpours missed the Sindh capital, Karachi. One did hit Pad Idan, where it left 60 mm of rain Wednesday. This was more than 20 times greater than the normal June rainfall.
It is still possible that this scenario is over wrought as to the intensity and spread of rain in Pakistan and northwestern India. However, it is the hunch of the present forecaster that some very unusual weather is going to unfold in the Subcontinent during the next week!