Deadly floods follow week of torrential rain in eastern Australia

Torrential rain has been hitting eastern Australia since Monday, with rainfall totals on the north-east coast widely achieving in excess of 100mm. In Yabulu, north of Townsville, there was major flooding on Tuesday as 196mm of rain fell within 24 hours. This was not the highest total recorded, however, with 244mm of rain falling on Tuesday at Mourilyan, near Innisfail on the Cassowary Coast.

The threat of heavy rain sank south across Queensland to the south-east, reaching Brisbane and the Sunshine Coast on Wednesday; stations in the south-east recorded up to 100mm, with a station in Dayboro recording 161mm. A further 100-150mm of rain fell on Friday across the south-east.

Communities in the Black Mountain region, Noosa, south-east Queensland, have become cut off as a consequence of flash flooding blocking roads, with alternative routes destroyed by a landslide during late February’s heavy rains. Road and school closures have littered Queensland and one woman died on Wednesday after having been swept away in a car in flash floods north of Mackay. River catchments have been inundated and the soils saturated after multiple heavy rain events over the past few months, with swollen rivers and dams full to bursting.

Monthly rainfall totals from all this look as if they will be more than three times higher than the monthly average widely across Queensland and northern New South Wales. The recent La Niña event strengthening the easterly winds across the equator has been driving these torrential rains, as increased moisture is fed in from the Pacific for these events.

Meanwhile, on Sunday, the tropical cyclones Asani and Karim were seen mirroring each other either side of the equator on satellite imagery. The cyclones developed in the Indian Ocean, with Asani sitting north of the equator to the east of India rotating anticlockwise, while Karim spun clockwise to the south. These differences in rotation are governed by the Coriolis force – this driving northern hemisphere winds to deflect to the right, and southern hemisphere winds deflecting to the left due to the Earth’s rotation. Asani gave some relief to eastern parts of India, which is in the grips of a heatwave, as cloud and rain reached eastern coasts on Wednesday. However, temperatures still reached a sweltering 46C (114.8F) in Gujarat, north-west India, on the same day.

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