It has been raining non-stop in Sydney this weekend with massive rain totals recorded between the Hunter and South coasts over the last 2 days. So where is this deluge coming from and when will it stop?!
Well, the atmosphere is completed saturated and when it's like this all it needs is a "trigger" for a heavy downpour. In this case, the "trigger" is a small-scale low pressure trough that formed off the NSW coast. The very moist air has been feeding into this trough causing widespread torrential rain in Sydney, the Hunter, South Coast and Illawarra. With so much heavy rain falling over a short time period, flash flooding is likely.
Over the last 48 hours, the heaviest falls have generally been in coastal suburbs, closest to this trough. In 24 hours to 9am Sunday morning, we've seen widespread falls of over 100mm with as much as 166mm in Little Bay, it's heaviest March rain since 1975. Other notable falls include:
Avalon- 139mm
St Ives- 179mm
Turrumurra- 175mm
Belrose- 137mm
North Manly-130mm
Sydney Airport- 100mm
Further south, Albion Park recorded 137mm, Wollongong 129mm and Barrengarry 210mm!! The rain has been lighter further west with up to 50mm in the Warragamba catchment area. Considering how dry it has been, this is unlikely to lead to any significant rises.
So- what next? Heavy rain will continue during Sunday, easing later as the trough moves away. But heavy rain is likely to return on Monday as another low pressure trough comes in from the west. The wet weather should start to ease on Tuesday.
