Other parts of the East Coast are gearing up for more flooding in the next few days.
So what is actually causing this rain?
Clouds may look fluffy and insubstantial, but they carry enormous amounts of water.
This equates to about 30 trillion liters of water. Or, using colloquial Australian measurements, 60 Sydney Harbor values (1 Sydharb = 500 gigaliters).
Why does it rain in the first place?
A mass of moist air rising from the surface expands as it moves higher in the atmosphere. This is because atmospheric pressure drops rapidly with altitude.
Even small clouds contain a lot of water. A cloud covering 1 cubic kilometer contains about 500 tons of water.
A low-pressure system means that the air pressure is lower than the surrounding area.
Warm air is less dense and is pushed up on top of cold air.
Why is there so much moisture in the air?
The La Niña events we have been experiencing for three consecutive years have cooled the waters of the central and eastern Pacific near the equator and warmed above average sea surface temperatures in the western Pacific, including around Australia.
For example, a third of Australia is more than twice as likely to receive rain during a La Niña period as under neutral conditions, and more than five times as likely as during an El Niño event.
Occasionally, however, more than a third of the continent will experience rain.
Rain, rain, go away
Keep your eyes on the horizon and look for clouds.
https://www.sbs.com.au/news/article/rain-rain-go-away-whats-behind-australias-rain-event/o4qmirfbo Australian Weather: What’s Behind the National Rain Event?