Flooding rains breathe life into the outback

It was just a few days ago that the driest part of the country- western QLD, northwest NSW and northeast SA- was being singed by a record-breaking heatwave. Today, this outback region is getting drenched by flooding rains! Urandangi in northwest QLD hasn't seen a drop in months, yet in just 24 hours a massive 42mm has fallen across the desert town.

Local flooding is already affecting southern areas of SA's Northeast Pastoral district thanks to 30-90mm of rain over the last few days. Another 50-70mm is possible by Thursday, further increasing the likelihood of flooding in the coming days.

What has caused this remarkable turn-around in the weather across the outback? There are two weather features at play. During the recent heatwave, northerly winds persistently churned extreme heat towards central Australia for about two weeks. But the hot air wasn't travelling on its own; the winds were also drawing in moisture from the tropics towards the central inland. Over the weekend, the south- eastern states got drenched thanks to a cold pool of air across the region. This cold pool has moved further north and tapped into this tongue of tropical moisture to produce flooding desert rains!

Is this normal? In one way it is. The climate of the outback is characterised by extreme variability. Prolonged dry periods followed by flooding rains are "normal" in this part of the world and that's what makes the arid zone so special. But it's quite unusual to see this much rain this early in the wet season. Flooding rains typically affect this region in December and January when tongues of tropical moisture feed into inland areas during periods of active monsoonal and tropical cyclone activity in the tropics. So this rain set-up is a little left of field for what we normally expect.