South-eastern Australia has been experiencing heavy rain since Thursday night, which will continue until Saturday morning local time. New South Wales will be particularly badly affected, with cumulative rainfall totals of 150-200m along coastal stretches.

Hourly totals are expected to reach 10-20mm at times, with the worst-affected areas potentially receiving 50mm within three hours. Strong winds are expected to accompany the heaviest downpours, with gusts of about 45mph (72km/h) at times.

Sydney is expected to be hit hard, and authorities have warned of life-threatening floods, notably along the Hawkesbury-Nepean River to the north-west of the city.

These conditions come as a result of cooler polar air moving in from the south meeting warmer tropical air to the north and forming a frontal boundary. This pattern repeated many times in 2022, Sydney’s wettest year on record.

After the main rain band has formed, an area of low pressure looks likely to develop around the Sydney region, further intensifying rainfall and increasing the risk of flooding. This low pressure will push southwards through the weekend, introducing rain and possibly thunderstorms to eastern Victoria, and potentially affecting the capital, Canberra.

Jiangxi province in China experienced severe thunderstorms last weekend, with frequent lightning, strong gusts and golf ball-sized hailstones. The winds reached category 12 on the local scale, equivalent to typhoon strength, which is unusual in inland parts of the country.

About 93,000 people were affected by these storms across nine cities. There were seven deaths, with local media reporting that three were due to people being blown from high-rise buildings. More than 2,500 homes were destroyed, and 800 people were displaced temporarily.

North-eastern areas of the US have also been experiencing unsettled weather. A storm pushed in from the south-west on Wednesday and Thursday, bringing gusts of more than 50mph and heavy rain. Flood warnings have been issued in many areas, and a number of homes are without power. The storm is forecast to move on to eastern Canada, and snow warnings have been issued for many areas with accumulations of 15-30cm possible.

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